diff --git a/java/com/google/gerrit/acceptance/InProcessProtocol.java b/java/com/google/gerrit/acceptance/InProcessProtocol.java
index de8d10ccf3..94c4635d40 100644
--- a/java/com/google/gerrit/acceptance/InProcessProtocol.java
+++ b/java/com/google/gerrit/acceptance/InProcessProtocol.java
@@ -246,7 +246,7 @@ class InProcessProtocol extends TestProtocol<Context> {
       try {
         perm.check(ProjectPermission.RUN_UPLOAD_PACK);
       } catch (AuthException e) {
-        throw new ServiceNotAuthorizedException();
+        throw new ServiceNotAuthorizedException(e.getMessage(), e);
       } catch (PermissionBackendException e) {
         throw new RuntimeException(e);
       }
@@ -318,7 +318,7 @@ class InProcessProtocol extends TestProtocol<Context> {
             .project(req.project)
             .check(ProjectPermission.RUN_RECEIVE_PACK);
       } catch (AuthException e) {
-        throw new ServiceNotAuthorizedException();
+        throw new ServiceNotAuthorizedException(e.getMessage(), e);
       } catch (PermissionBackendException e) {
         throw new RuntimeException(e);
       }
diff --git a/java/com/google/gerrit/common/errors/InvalidSshKeyException.java b/java/com/google/gerrit/common/errors/InvalidSshKeyException.java
index 3398417a98..0e5d80d8ee 100644
--- a/java/com/google/gerrit/common/errors/InvalidSshKeyException.java
+++ b/java/com/google/gerrit/common/errors/InvalidSshKeyException.java
@@ -23,4 +23,8 @@ public class InvalidSshKeyException extends Exception {
   public InvalidSshKeyException() {
     super(MESSAGE);
   }
+
+  public InvalidSshKeyException(Throwable cause) {
+    super(MESSAGE, cause);
+  }
 }
diff --git a/java/com/google/gerrit/extensions/restapi/MethodNotAllowedException.java b/java/com/google/gerrit/extensions/restapi/MethodNotAllowedException.java
index 61c6345e4e..235b77f4ec 100644
--- a/java/com/google/gerrit/extensions/restapi/MethodNotAllowedException.java
+++ b/java/com/google/gerrit/extensions/restapi/MethodNotAllowedException.java
@@ -26,4 +26,12 @@ public class MethodNotAllowedException extends RestApiException {
   public MethodNotAllowedException(String msg) {
     super(msg);
   }
+
+  /**
+   * @param msg error text for client describing why the method is not allowed.
+   * @param cause reason for the method not being allowed.
+   */
+  public MethodNotAllowedException(String msg, Throwable cause) {
+    super(msg, cause);
+  }
 }
diff --git a/java/com/google/gerrit/extensions/restapi/NotImplementedException.java b/java/com/google/gerrit/extensions/restapi/NotImplementedException.java
index 566159d850..d74986a700 100644
--- a/java/com/google/gerrit/extensions/restapi/NotImplementedException.java
+++ b/java/com/google/gerrit/extensions/restapi/NotImplementedException.java
@@ -25,4 +25,8 @@ public class NotImplementedException extends UnsupportedOperationException {
   public NotImplementedException(String message) {
     super(message);
   }
+
+  public NotImplementedException(String message, Throwable cause) {
+    super(message, cause);
+  }
 }
diff --git a/java/com/google/gerrit/extensions/restapi/ResourceNotFoundException.java b/java/com/google/gerrit/extensions/restapi/ResourceNotFoundException.java
index e67682878b..fa2288aa84 100644
--- a/java/com/google/gerrit/extensions/restapi/ResourceNotFoundException.java
+++ b/java/com/google/gerrit/extensions/restapi/ResourceNotFoundException.java
@@ -34,6 +34,10 @@ public class ResourceNotFoundException extends RestApiException {
     super("Not found: " + id.get());
   }
 
+  public ResourceNotFoundException(IdString id, Throwable cause) {
+    super("Not found: " + id.get(), cause);
+  }
+
   @SuppressWarnings("unchecked")
   @Override
   public ResourceNotFoundException caching(CacheControl c) {
diff --git a/java/com/google/gerrit/httpd/HtmlDomUtil.java b/java/com/google/gerrit/httpd/HtmlDomUtil.java
index 25ae71cee8..57f2664184 100644
--- a/java/com/google/gerrit/httpd/HtmlDomUtil.java
+++ b/java/com/google/gerrit/httpd/HtmlDomUtil.java
@@ -131,7 +131,7 @@ public class HtmlDomUtil {
     try {
       d = newBuilder().newDocument();
     } catch (ParserConfigurationException e) {
-      throw new IOException("Cannot clone document");
+      throw new IOException("Cannot clone document", e);
     }
     Node n = d.importNode(doc.getDocumentElement(), true);
     d.appendChild(n);
diff --git a/java/com/google/gerrit/httpd/ProjectOAuthFilter.java b/java/com/google/gerrit/httpd/ProjectOAuthFilter.java
index 30ebe6e7cb..4461a52fa1 100644
--- a/java/com/google/gerrit/httpd/ProjectOAuthFilter.java
+++ b/java/com/google/gerrit/httpd/ProjectOAuthFilter.java
@@ -195,7 +195,7 @@ class ProjectOAuthFilter implements Filter {
       defaultAuthPlugin = loginProvider.getPluginName();
       defaultAuthProvider = loginProvider.getExportName();
     } catch (NoSuchElementException e) {
-      throw new ServletException("No OAuth login provider installed");
+      throw new ServletException("No OAuth login provider installed", e);
     } catch (IllegalArgumentException e) {
       // multiple providers found => do not pick any
     }
diff --git a/java/com/google/gerrit/httpd/plugins/PluginServletContext.java b/java/com/google/gerrit/httpd/plugins/PluginServletContext.java
index 6a8ef328f5..40083e441e 100644
--- a/java/com/google/gerrit/httpd/plugins/PluginServletContext.java
+++ b/java/com/google/gerrit/httpd/plugins/PluginServletContext.java
@@ -61,9 +61,11 @@ class PluginServletContext {
       try {
         handler = API.class.getDeclaredMethod(method.getName(), method.getParameterTypes());
       } catch (NoSuchMethodException e) {
-        throw new NoSuchMethodError(
+        String msg =
             String.format(
-                "%s does not implement %s", PluginServletContext.class, method.toGenericString()));
+                "%s does not implement %s", PluginServletContext.class, method.toGenericString());
+        logger.atSevere().withCause(e).log(msg);
+        throw new NoSuchMethodError(msg);
       }
       return handler.invoke(this, args);
     }
diff --git a/java/com/google/gerrit/httpd/raw/BazelBuild.java b/java/com/google/gerrit/httpd/raw/BazelBuild.java
index 430f0b518d..3dd46356f5 100644
--- a/java/com/google/gerrit/httpd/raw/BazelBuild.java
+++ b/java/com/google/gerrit/httpd/raw/BazelBuild.java
@@ -63,8 +63,9 @@ public class BazelBuild {
     try {
       status = rebuild.waitFor();
     } catch (InterruptedException e) {
-      throw new InterruptedIOException(
-          "interrupted waiting for: " + Joiner.on(' ').join(proc.command()));
+      String msg = "interrupted waiting for: " + Joiner.on(' ').join(proc.command());
+      logger.atSevere().withCause(e).log(msg);
+      throw new InterruptedIOException(msg);
     }
     if (status != 0) {
       logger.atWarning().log("build failed: %s", new String(out, UTF_8));
diff --git a/java/com/google/gerrit/httpd/restapi/RestApiServlet.java b/java/com/google/gerrit/httpd/restapi/RestApiServlet.java
index 8000dbe6dc..5f14795113 100644
--- a/java/com/google/gerrit/httpd/restapi/RestApiServlet.java
+++ b/java/com/google/gerrit/httpd/restapi/RestApiServlet.java
@@ -875,7 +875,7 @@ public class RestApiServlet extends HttpServlet {
           try {
             first = json.peek();
           } catch (EOFException e) {
-            throw new BadRequestException("Expected JSON object");
+            throw new BadRequestException("Expected JSON object", e);
           }
           if (first == JsonToken.STRING) {
             return parseString(json.nextString(), type);
diff --git a/java/com/google/gerrit/httpd/rpc/project/ProjectAccessFactory.java b/java/com/google/gerrit/httpd/rpc/project/ProjectAccessFactory.java
index 6193e458c5..3afb0e2004 100644
--- a/java/com/google/gerrit/httpd/rpc/project/ProjectAccessFactory.java
+++ b/java/com/google/gerrit/httpd/rpc/project/ProjectAccessFactory.java
@@ -268,7 +268,7 @@ class ProjectAccessFactory extends Handler<ProjectAccess> {
     try {
       permissionBackend.currentUser().project(projectName).check(permissionToCheck);
     } catch (AuthException e) {
-      throw new NoSuchProjectException(projectName);
+      throw new NoSuchProjectException(projectName, e);
     }
     state.checkStatePermitsRead();
     return state;
diff --git a/java/com/google/gerrit/httpd/rpc/project/ProjectAccessHandler.java b/java/com/google/gerrit/httpd/rpc/project/ProjectAccessHandler.java
index 44c896681c..552e712f6c 100644
--- a/java/com/google/gerrit/httpd/rpc/project/ProjectAccessHandler.java
+++ b/java/com/google/gerrit/httpd/rpc/project/ProjectAccessHandler.java
@@ -194,7 +194,7 @@ public abstract class ProjectAccessHandler<T> extends Handler<T> {
 
       return updateProjectConfig(config, md, parentProjectUpdate);
     } catch (RepositoryNotFoundException notFound) {
-      throw new NoSuchProjectException(projectName);
+      throw new NoSuchProjectException(projectName, notFound);
     }
   }
 
diff --git a/java/com/google/gerrit/lucene/QueryBuilder.java b/java/com/google/gerrit/lucene/QueryBuilder.java
index ce5ba9859a..8dfc12ecf4 100644
--- a/java/com/google/gerrit/lucene/QueryBuilder.java
+++ b/java/com/google/gerrit/lucene/QueryBuilder.java
@@ -167,7 +167,7 @@ public class QueryBuilder<V> {
       // subclasses of OperatorPredicate.
       value = Integer.parseInt(p.getValue());
     } catch (NumberFormatException e) {
-      throw new QueryParseException("not an integer: " + p.getValue());
+      throw new QueryParseException("not an integer: " + p.getValue(), e);
     }
     return new TermQuery(intTerm(p.getField().getName(), value));
   }
diff --git a/java/com/google/gerrit/pgm/init/BaseInit.java b/java/com/google/gerrit/pgm/init/BaseInit.java
index 8614347a02..234abfdded 100644
--- a/java/com/google/gerrit/pgm/init/BaseInit.java
+++ b/java/com/google/gerrit/pgm/init/BaseInit.java
@@ -356,7 +356,7 @@ public class BaseInit extends SiteProgram {
       IoUtil.loadJARs(secureStoreLib);
       return new SecureStoreInitData(secureStoreLib, secureStores.get(0));
     } catch (IOException e) {
-      throw new InvalidSecureStoreException(String.format("%s is not a valid jar", secureStore));
+      throw new InvalidSecureStoreException(String.format("%s is not a valid jar", secureStore), e);
     }
   }
 
diff --git a/java/com/google/gerrit/pgm/init/InitHttpd.java b/java/com/google/gerrit/pgm/init/InitHttpd.java
index d583ea550d..ada4ac5ddc 100644
--- a/java/com/google/gerrit/pgm/init/InitHttpd.java
+++ b/java/com/google/gerrit/pgm/init/InitHttpd.java
@@ -169,7 +169,7 @@ class InitHttpd implements InitStep {
         uri = new URI(s + "://" + uri.getHost() + uri.getPath());
       }
     } catch (URISyntaxException e) {
-      throw die("invalid httpd.listenUrl");
+      throw die("invalid httpd.listenUrl", e);
     }
     httpd.set("listenUrl", urlbuf.toString());
     gerrit.string("Canonical URL", "canonicalWebUrl", uri.toString());
diff --git a/java/com/google/gerrit/pgm/init/Libraries.java b/java/com/google/gerrit/pgm/init/Libraries.java
index c599e99eb8..826a79b2a2 100644
--- a/java/com/google/gerrit/pgm/init/Libraries.java
+++ b/java/com/google/gerrit/pgm/init/Libraries.java
@@ -71,7 +71,7 @@ class Libraries {
         try {
           f.set(this, downloadProvider.get());
         } catch (IllegalArgumentException | IllegalAccessException e) {
-          throw new IllegalStateException("Cannot initialize " + f.getName());
+          throw new IllegalStateException("Cannot initialize " + f.getName(), e);
         }
       }
     }
@@ -84,7 +84,7 @@ class Libraries {
             | IllegalAccessException
             | NoSuchFieldException
             | SecurityException e) {
-          throw new IllegalStateException("Cannot configure " + f.getName());
+          throw new IllegalStateException("Cannot configure " + f.getName(), e);
         }
       }
     }
diff --git a/java/com/google/gerrit/server/ApprovalsUtil.java b/java/com/google/gerrit/server/ApprovalsUtil.java
index 3625de6a45..e2b7c6985e 100644
--- a/java/com/google/gerrit/server/ApprovalsUtil.java
+++ b/java/com/google/gerrit/server/ApprovalsUtil.java
@@ -372,7 +372,7 @@ public class ApprovalsUtil {
         forChange.check(new LabelPermission.WithValue(name, value));
       } catch (AuthException e) {
         throw new AuthException(
-            String.format("applying label \"%s\": %d is restricted", name, value));
+            String.format("applying label \"%s\": %d is restricted", name, value), e);
       }
     }
   }
diff --git a/java/com/google/gerrit/server/account/AccountManager.java b/java/com/google/gerrit/server/account/AccountManager.java
index b0dc8a389c..0772bb3ac1 100644
--- a/java/com/google/gerrit/server/account/AccountManager.java
+++ b/java/com/google/gerrit/server/account/AccountManager.java
@@ -390,7 +390,7 @@ public class AccountManager {
     try {
       groupsUpdate.updateGroup(groupUuid, groupUpdate);
     } catch (NoSuchGroupException e) {
-      throw new AccountException(String.format("Group %s not found", groupUuid));
+      throw new AccountException(String.format("Group %s not found", groupUuid), e);
     }
   }
 
diff --git a/java/com/google/gerrit/server/account/externalids/ExternalId.java b/java/com/google/gerrit/server/account/externalids/ExternalId.java
index c363b5bf03..9baa7dd60f 100644
--- a/java/com/google/gerrit/server/account/externalids/ExternalId.java
+++ b/java/com/google/gerrit/server/account/externalids/ExternalId.java
@@ -24,6 +24,7 @@ import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
+import com.google.common.flogger.FluentLogger;
 import com.google.common.hash.Hashing;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.extensions.client.AuthType;
@@ -43,6 +44,8 @@ import org.eclipse.jgit.lib.ObjectId;
 
 @AutoValue
 public abstract class ExternalId implements Serializable {
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
   // If these regular expressions are modified the same modifications should be done to the
   // corresponding regular expressions in the
   // com.google.gerrit.client.account.UsernameField class.
@@ -391,11 +394,12 @@ public abstract class ExternalId implements Serializable {
       }
       return accountId;
     } catch (IllegalArgumentException e) {
-      throw invalidConfig(
-          noteId,
+      String msg =
           String.format(
               "Value %s for '%s.%s.%s' is invalid, expected account ID",
-              accountIdStr, EXTERNAL_ID_SECTION, externalIdKeyStr, ACCOUNT_ID_KEY));
+              accountIdStr, EXTERNAL_ID_SECTION, externalIdKeyStr, ACCOUNT_ID_KEY);
+      logger.atSevere().withCause(e).log(msg);
+      throw invalidConfig(noteId, msg);
     }
   }
 
diff --git a/java/com/google/gerrit/server/args4j/AccountIdHandler.java b/java/com/google/gerrit/server/args4j/AccountIdHandler.java
index 2b66334f74..512937ba22 100644
--- a/java/com/google/gerrit/server/args4j/AccountIdHandler.java
+++ b/java/com/google/gerrit/server/args4j/AccountIdHandler.java
@@ -16,6 +16,7 @@ package com.google.gerrit.server.args4j;
 
 import static com.google.gerrit.util.cli.Localizable.localizable;
 
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.extensions.client.AuthType;
 import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.server.account.AccountException;
@@ -37,6 +38,8 @@ import org.kohsuke.args4j.spi.Parameters;
 import org.kohsuke.args4j.spi.Setter;
 
 public class AccountIdHandler extends OptionHandler<Account.Id> {
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
   private final AccountResolver accountResolver;
   private final AccountManager accountManager;
   private final AuthType authType;
@@ -82,7 +85,9 @@ public class AccountIdHandler extends OptionHandler<Account.Id> {
         }
       }
     } catch (OrmException e) {
-      throw new CmdLineException(owner, localizable("database is down"));
+      String msg = "database is down";
+      logger.atSevere().withCause(e).log(msg);
+      throw new CmdLineException(owner, localizable(msg));
     } catch (IOException e) {
       throw new CmdLineException(owner, "Failed to load account", e);
     } catch (ConfigInvalidException e) {
@@ -102,7 +107,9 @@ public class AccountIdHandler extends OptionHandler<Account.Id> {
       req.setSkipAuthentication(true);
       return accountManager.authenticate(req).getAccountId();
     } catch (AccountException e) {
-      throw new CmdLineException(owner, localizable("user \"%s\" not found"), user);
+      String msg = "user \"%s\" not found";
+      logger.atSevere().withCause(e).log(msg, user);
+      throw new CmdLineException(owner, localizable(msg), user);
     }
   }
 
diff --git a/java/com/google/gerrit/server/args4j/ChangeIdHandler.java b/java/com/google/gerrit/server/args4j/ChangeIdHandler.java
index 13832fabb0..eec3eb013b 100644
--- a/java/com/google/gerrit/server/args4j/ChangeIdHandler.java
+++ b/java/com/google/gerrit/server/args4j/ChangeIdHandler.java
@@ -66,7 +66,7 @@ public class ChangeIdHandler extends OptionHandler<Change.Id> {
         return 1;
       }
     } catch (IllegalArgumentException e) {
-      throw new CmdLineException(owner, localizable("Change-Id is not valid"));
+      throw new CmdLineException(owner, localizable("Change-Id is not valid: %s"), e.getMessage());
     } catch (OrmException e) {
       throw new CmdLineException(owner, localizable("Database error: %s"), e.getMessage());
     }
diff --git a/java/com/google/gerrit/server/args4j/PatchSetIdHandler.java b/java/com/google/gerrit/server/args4j/PatchSetIdHandler.java
index 84c1d88d2a..4581fe02dc 100644
--- a/java/com/google/gerrit/server/args4j/PatchSetIdHandler.java
+++ b/java/com/google/gerrit/server/args4j/PatchSetIdHandler.java
@@ -43,7 +43,8 @@ public class PatchSetIdHandler extends OptionHandler<PatchSet.Id> {
     try {
       id = PatchSet.Id.parse(token);
     } catch (IllegalArgumentException e) {
-      throw new CmdLineException(owner, localizable("\"%s\" is not a valid patch set"), token);
+      throw new CmdLineException(
+          owner, localizable("\"%s\" is not a valid patch set: %s"), token, e.getMessage());
     }
 
     setter.addValue(id);
diff --git a/java/com/google/gerrit/server/args4j/ProjectHandler.java b/java/com/google/gerrit/server/args4j/ProjectHandler.java
index 223b112563..52fadd242d 100644
--- a/java/com/google/gerrit/server/args4j/ProjectHandler.java
+++ b/java/com/google/gerrit/server/args4j/ProjectHandler.java
@@ -89,7 +89,7 @@ public class ProjectHandler extends OptionHandler<ProjectState> {
       permissionBackend.currentUser().project(nameKey).check(permissionToCheck);
     } catch (AuthException e) {
       throw new CmdLineException(
-          owner, localizable(new NoSuchProjectException(nameKey).getMessage()));
+          owner, localizable(new NoSuchProjectException(nameKey, e).getMessage()));
     } catch (PermissionBackendException | IOException e) {
       logger.atWarning().withCause(e).log("Cannot load project %s", nameWithoutSuffix);
       throw new CmdLineException(
diff --git a/java/com/google/gerrit/server/cache/serialize/IntegerCacheSerializer.java b/java/com/google/gerrit/server/cache/serialize/IntegerCacheSerializer.java
index 449445436b..aca9b05b5e 100644
--- a/java/com/google/gerrit/server/cache/serialize/IntegerCacheSerializer.java
+++ b/java/com/google/gerrit/server/cache/serialize/IntegerCacheSerializer.java
@@ -37,7 +37,7 @@ public enum IntegerCacheSerializer implements CacheSerializer<Integer> {
       cout.writeInt32NoTag(requireNonNull(object));
       cout.flush();
     } catch (IOException e) {
-      throw new IllegalStateException("Failed to serialize int");
+      throw new IllegalStateException("Failed to serialize int", e);
     }
     int n = cout.getTotalBytesWritten();
     return n == buf.length ? buf : Arrays.copyOfRange(buf, 0, n);
@@ -50,7 +50,7 @@ public enum IntegerCacheSerializer implements CacheSerializer<Integer> {
     try {
       ret = cin.readRawVarint32();
     } catch (IOException e) {
-      throw new IllegalArgumentException("Failed to deserialize int");
+      throw new IllegalArgumentException("Failed to deserialize int", e);
     }
     int n = cin.getTotalBytesRead();
     if (n != in.length) {
diff --git a/java/com/google/gerrit/server/change/PureRevert.java b/java/com/google/gerrit/server/change/PureRevert.java
index ddc9661cc2..766b82f13a 100644
--- a/java/com/google/gerrit/server/change/PureRevert.java
+++ b/java/com/google/gerrit/server/change/PureRevert.java
@@ -94,7 +94,7 @@ public class PureRevert {
       try {
         claimedOriginalCommit = rw.parseCommit(ObjectId.fromString(claimedOriginal));
       } catch (InvalidObjectIdException | MissingObjectException e) {
-        throw new BadRequestException("invalid object ID");
+        throw new BadRequestException("invalid object ID", e);
       }
       if (claimedOriginalCommit.getParentCount() == 0) {
         throw new BadRequestException("can't check against initial commit");
diff --git a/java/com/google/gerrit/server/change/WorkInProgressOp.java b/java/com/google/gerrit/server/change/WorkInProgressOp.java
index 35b4e6ee86..71cb4c4639 100644
--- a/java/com/google/gerrit/server/change/WorkInProgressOp.java
+++ b/java/com/google/gerrit/server/change/WorkInProgressOp.java
@@ -83,7 +83,7 @@ public class WorkInProgressOp implements BatchUpdateOp {
           .project(change.getProject())
           .check(ProjectPermission.WRITE_CONFIG);
     } catch (AuthException exp) {
-      throw new AuthException("not allowed to toggle work in progress");
+      throw new AuthException("not allowed to toggle work in progress", exp);
     }
   }
 
diff --git a/java/com/google/gerrit/server/config/ConfigUtil.java b/java/com/google/gerrit/server/config/ConfigUtil.java
index f476adf1ec..43c05e0e64 100644
--- a/java/com/google/gerrit/server/config/ConfigUtil.java
+++ b/java/com/google/gerrit/server/config/ConfigUtil.java
@@ -30,7 +30,6 @@ import org.eclipse.jgit.errors.ConfigInvalidException;
 import org.eclipse.jgit.lib.Config;
 
 public class ConfigUtil {
-
   @SuppressWarnings("unchecked")
   private static <T> T[] allValuesOf(T defaultValue) {
     try {
@@ -182,7 +181,7 @@ public class ConfigUtil {
     try {
       return getTimeUnit(s, defaultValue, wantUnit);
     } catch (IllegalArgumentException notTime) {
-      throw notTimeUnit(section, subsection, setting, valueString);
+      throw notTimeUnit(section, subsection, setting, valueString, notTime);
     }
   }
 
@@ -250,7 +249,7 @@ public class ConfigUtil {
     try {
       return wantUnit.convert(Long.parseLong(digits) * inputMul, inputUnit);
     } catch (NumberFormatException nfe) {
-      throw notTimeUnit(valueString);
+      throw notTimeUnit(valueString, nfe);
     }
   }
 
@@ -421,13 +420,21 @@ public class ConfigUtil {
   }
 
   private static IllegalArgumentException notTimeUnit(
-      final String section,
-      final String subsection,
-      final String setting,
-      final String valueString) {
-    return new IllegalArgumentException(
-        "Invalid time unit value: "
-            + section
+      String section, String subsection, String setting, String valueString, Throwable why) {
+    return notTimeUnit(
+        section
+            + (subsection != null ? "." + subsection : "")
+            + "."
+            + setting
+            + " = "
+            + valueString,
+        why);
+  }
+
+  private static IllegalArgumentException notTimeUnit(
+      String section, String subsection, String setting, String valueString) {
+    return notTimeUnit(
+        section
             + (subsection != null ? "." + subsection : "")
             + "."
             + setting
@@ -439,5 +446,9 @@ public class ConfigUtil {
     return new IllegalArgumentException("Invalid time unit value: " + val);
   }
 
+  private static IllegalArgumentException notTimeUnit(String val, Throwable why) {
+    return new IllegalArgumentException("Invalid time unit value: " + val, why);
+  }
+
   private ConfigUtil() {}
 }
diff --git a/java/com/google/gerrit/server/git/MergeUtil.java b/java/com/google/gerrit/server/git/MergeUtil.java
index b6c5f25f64..8922587ca0 100644
--- a/java/com/google/gerrit/server/git/MergeUtil.java
+++ b/java/com/google/gerrit/server/git/MergeUtil.java
@@ -745,6 +745,7 @@ public class MergeUtil {
       try {
         failed(rw, mergeTip, n, getCommitMergeStatus(e.getReason()));
       } catch (IOException e2) {
+        logger.atSevere().withCause(e2).log("Failed to set merge failure status for " + n.name());
         throw new IntegrationException("Cannot merge " + n.name(), e);
       }
     } catch (IOException e) {
diff --git a/java/com/google/gerrit/server/git/validators/CommitValidationException.java b/java/com/google/gerrit/server/git/validators/CommitValidationException.java
index bffe382d89..aeead6382b 100644
--- a/java/com/google/gerrit/server/git/validators/CommitValidationException.java
+++ b/java/com/google/gerrit/server/git/validators/CommitValidationException.java
@@ -27,6 +27,11 @@ public class CommitValidationException extends ValidationException {
     this.messages = ImmutableList.of(message);
   }
 
+  public CommitValidationException(String reason, CommitValidationMessage message, Throwable why) {
+    super(reason, why);
+    this.messages = ImmutableList.of(message);
+  }
+
   public CommitValidationException(String reason, List<CommitValidationMessage> messages) {
     super(reason);
     this.messages = ImmutableList.copyOf(messages);
diff --git a/java/com/google/gerrit/server/git/validators/CommitValidators.java b/java/com/google/gerrit/server/git/validators/CommitValidators.java
index 7ab2ada0dc..ceb624901d 100644
--- a/java/com/google/gerrit/server/git/validators/CommitValidators.java
+++ b/java/com/google/gerrit/server/git/validators/CommitValidators.java
@@ -465,7 +465,7 @@ public class CommitValidators {
         perm.check(RefPermission.MERGE);
         return Collections.emptyList();
       } catch (AuthException e) {
-        throw new CommitValidationException("you are not allowed to upload merges");
+        throw new CommitValidationException("you are not allowed to upload merges", e);
       } catch (PermissionBackendException e) {
         logger.atSevere().withCause(e).log("cannot check MERGE");
         throw new CommitValidationException("internal auth error");
@@ -562,7 +562,7 @@ public class CommitValidators {
           perm.check(RefPermission.FORGE_COMMITTER);
         } catch (AuthException denied) {
           throw new CommitValidationException(
-              "not Signed-off-by author/committer/uploader in message footer");
+              "not Signed-off-by author/committer/uploader in message footer", denied);
         } catch (PermissionBackendException e) {
           logger.atSevere().withCause(e).log("cannot check FORGE_COMMITTER");
           throw new CommitValidationException("internal auth error");
@@ -597,7 +597,7 @@ public class CommitValidators {
         return Collections.emptyList();
       } catch (AuthException e) {
         throw new CommitValidationException(
-            "invalid author", invalidEmail("author", author, user, urlFormatter));
+            "invalid author", invalidEmail("author", author, user, urlFormatter), e);
       } catch (PermissionBackendException e) {
         logger.atSevere().withCause(e).log("cannot check FORGE_AUTHOR");
         throw new CommitValidationException("internal auth error");
@@ -630,7 +630,7 @@ public class CommitValidators {
         return Collections.emptyList();
       } catch (AuthException e) {
         throw new CommitValidationException(
-            "invalid committer", invalidEmail("committer", committer, user, urlFormatter));
+            "invalid committer", invalidEmail("committer", committer, user, urlFormatter), e);
       } catch (PermissionBackendException e) {
         logger.atSevere().withCause(e).log("cannot check FORGE_COMMITTER");
         throw new CommitValidationException("internal auth error");
@@ -669,7 +669,8 @@ public class CommitValidators {
                   "pushing merge commit %s by %s requires '%s' permission",
                   receiveEvent.commit.getId(),
                   gerritIdent.getEmailAddress(),
-                  RefPermission.FORGE_SERVER.name()));
+                  RefPermission.FORGE_SERVER.name()),
+              denied);
         } catch (PermissionBackendException e) {
           logger.atSevere().withCause(e).log("cannot check FORGE_SERVER");
           throw new CommitValidationException("internal auth error");
diff --git a/java/com/google/gerrit/server/git/validators/MergeValidationException.java b/java/com/google/gerrit/server/git/validators/MergeValidationException.java
index 3624fe03a2..2b7803d636 100644
--- a/java/com/google/gerrit/server/git/validators/MergeValidationException.java
+++ b/java/com/google/gerrit/server/git/validators/MergeValidationException.java
@@ -28,4 +28,8 @@ public class MergeValidationException extends ValidationException {
   public MergeValidationException(String msg) {
     super(msg);
   }
+
+  public MergeValidationException(String msg, Throwable why) {
+    super(msg, why);
+  }
 }
diff --git a/java/com/google/gerrit/server/git/validators/MergeValidators.java b/java/com/google/gerrit/server/git/validators/MergeValidators.java
index 0422c51f1b..425ab3fcf7 100644
--- a/java/com/google/gerrit/server/git/validators/MergeValidators.java
+++ b/java/com/google/gerrit/server/git/validators/MergeValidators.java
@@ -177,7 +177,7 @@ public class MergeValidators {
                 try {
                   permissionBackend.user(caller).check(GlobalPermission.ADMINISTRATE_SERVER);
                 } catch (AuthException e) {
-                  throw new MergeValidationException(SET_BY_ADMIN);
+                  throw new MergeValidationException(SET_BY_ADMIN, e);
                 } catch (PermissionBackendException e) {
                   logger.atWarning().withCause(e).log("Cannot check ADMINISTRATE_SERVER");
                   throw new MergeValidationException("validation unavailable");
@@ -189,7 +189,7 @@ public class MergeValidators {
                       .project(destProject.getNameKey())
                       .check(ProjectPermission.WRITE_CONFIG);
                 } catch (AuthException e) {
-                  throw new MergeValidationException(SET_BY_OWNER);
+                  throw new MergeValidationException(SET_BY_OWNER, e);
                 } catch (PermissionBackendException e) {
                   logger.atWarning().withCause(e).log("Cannot check WRITE_CONFIG");
                   throw new MergeValidationException("validation unavailable");
@@ -230,7 +230,7 @@ public class MergeValidators {
             }
           }
         } catch (ConfigInvalidException | IOException e) {
-          throw new MergeValidationException(INVALID_CONFIG);
+          throw new MergeValidationException(INVALID_CONFIG, e);
         }
       }
     }
diff --git a/java/com/google/gerrit/server/git/validators/RefOperationValidators.java b/java/com/google/gerrit/server/git/validators/RefOperationValidators.java
index acae533b7e..4eb317ced8 100644
--- a/java/com/google/gerrit/server/git/validators/RefOperationValidators.java
+++ b/java/com/google/gerrit/server/git/validators/RefOperationValidators.java
@@ -131,7 +131,7 @@ public class RefOperationValidators {
             try {
               perm.check(GlobalPermission.ACCESS_DATABASE);
             } catch (AuthException | PermissionBackendException e) {
-              throw new ValidationException("Not allowed to create user branch.");
+              throw new ValidationException("Not allowed to create user branch.", e);
             }
             if (Account.Id.fromRef(refEvent.command.getRefName()) == null) {
               throw new ValidationException(
@@ -142,7 +142,7 @@ public class RefOperationValidators {
             try {
               perm.check(GlobalPermission.ACCESS_DATABASE);
             } catch (AuthException | PermissionBackendException e) {
-              throw new ValidationException("Not allowed to delete user branch.");
+              throw new ValidationException("Not allowed to delete user branch.", e);
             }
           }
         }
diff --git a/java/com/google/gerrit/server/mail/send/ChangeEmail.java b/java/com/google/gerrit/server/mail/send/ChangeEmail.java
index a1b20afc5c..a3000eb91a 100644
--- a/java/com/google/gerrit/server/mail/send/ChangeEmail.java
+++ b/java/com/google/gerrit/server/mail/send/ChangeEmail.java
@@ -299,7 +299,7 @@ public abstract class ChangeEmail extends NotificationEmail {
             args.patchSetUtil.get(
                 changeData.db(), changeData.notes(), new PatchSet.Id(change.getId(), patchSetId));
       } catch (OrmException e) {
-        throw new PatchListNotAvailableException("Failed to get patchSet");
+        throw new PatchListNotAvailableException("Failed to get patchSet", e);
       }
     }
     return args.patchListCache.get(change, ps);
diff --git a/java/com/google/gerrit/server/notedb/ChangeNotesParser.java b/java/com/google/gerrit/server/notedb/ChangeNotesParser.java
index cbb7020207..98cbd02994 100644
--- a/java/com/google/gerrit/server/notedb/ChangeNotesParser.java
+++ b/java/com/google/gerrit/server/notedb/ChangeNotesParser.java
@@ -926,7 +926,9 @@ class ChangeNotesParser {
     try {
       adr = Address.parse(line);
     } catch (IllegalArgumentException e) {
-      throw invalidFooter(state.getByEmailFooterKey(), line);
+      ConfigInvalidException cie = invalidFooter(state.getByEmailFooterKey(), line);
+      cie.initCause(e);
+      throw cie;
     }
     if (!reviewersByEmail.containsRow(adr)) {
       reviewersByEmail.put(adr, state, ts);
diff --git a/java/com/google/gerrit/server/patch/PatchScriptFactory.java b/java/com/google/gerrit/server/patch/PatchScriptFactory.java
index b1e0e3cf68..bfcb3255b0 100644
--- a/java/com/google/gerrit/server/patch/PatchScriptFactory.java
+++ b/java/com/google/gerrit/server/patch/PatchScriptFactory.java
@@ -206,7 +206,7 @@ public class PatchScriptFactory implements Callable<PatchScript> {
       try {
         permissionBackend.currentUser().change(notes).database(db).check(ChangePermission.READ);
       } catch (AuthException e) {
-        throw new NoSuchChangeException(changeId);
+        throw new NoSuchChangeException(changeId, e);
       }
     }
 
diff --git a/java/com/google/gerrit/server/project/RefUtil.java b/java/com/google/gerrit/server/project/RefUtil.java
index 4e08137a1c..a9c964dd51 100644
--- a/java/com/google/gerrit/server/project/RefUtil.java
+++ b/java/com/google/gerrit/server/project/RefUtil.java
@@ -55,7 +55,7 @@ public class RefUtil {
           "Cannot resolve \"%s\" in project \"%s\"", baseRevision, projectName.get());
       throw new InvalidRevisionException(baseRevision);
     } catch (RevisionSyntaxException err) {
-      throw new InvalidRevisionException(baseRevision);
+      throw new InvalidRevisionException(baseRevision, err);
     }
   }
 
@@ -66,7 +66,7 @@ public class RefUtil {
       try {
         rw.markStart(rw.parseCommit(revid));
       } catch (IncorrectObjectTypeException err) {
-        throw new InvalidRevisionException(revid.name());
+        throw new InvalidRevisionException(revid.name(), err);
       }
       RefDatabase refDb = repo.getRefDatabase();
       Iterable<Ref> refs =
@@ -86,7 +86,7 @@ public class RefUtil {
       rw.checkConnectivity();
       return rw;
     } catch (IncorrectObjectTypeException | MissingObjectException err) {
-      throw new InvalidRevisionException(revid.name());
+      throw new InvalidRevisionException(revid.name(), err);
     } catch (IOException err) {
       logger.atSevere().withCause(err).log(
           "Repository \"%s\" may be corrupt; suggest running git fsck", repo.getDirectory());
@@ -128,5 +128,9 @@ public class RefUtil {
     InvalidRevisionException(@Nullable String invalidRevision) {
       super(MESSAGE + ": " + invalidRevision);
     }
+
+    InvalidRevisionException(@Nullable String invalidRevision, Throwable why) {
+      super(MESSAGE + ": " + invalidRevision, why);
+    }
   }
 }
diff --git a/java/com/google/gerrit/server/query/account/AccountQueryBuilder.java b/java/com/google/gerrit/server/query/account/AccountQueryBuilder.java
index 148c63352b..feb9ccbe35 100644
--- a/java/com/google/gerrit/server/query/account/AccountQueryBuilder.java
+++ b/java/com/google/gerrit/server/query/account/AccountQueryBuilder.java
@@ -132,7 +132,9 @@ public class AccountQueryBuilder extends QueryBuilder<AccountState> {
           .change(changeNotes)
           .check(ChangePermission.READ);
     } catch (AuthException e) {
-      throw error(String.format("change %s not found", change));
+      String msg = String.format("change %s not found", change);
+      logger.atSevere().withCause(e).log(msg);
+      throw error(msg);
     }
 
     return AccountPredicates.cansee(args, changeNotes);
diff --git a/java/com/google/gerrit/server/query/project/ProjectQueryBuilder.java b/java/com/google/gerrit/server/query/project/ProjectQueryBuilder.java
index 4923015faa..57db5e7278 100644
--- a/java/com/google/gerrit/server/query/project/ProjectQueryBuilder.java
+++ b/java/com/google/gerrit/server/query/project/ProjectQueryBuilder.java
@@ -75,7 +75,7 @@ public class ProjectQueryBuilder extends QueryBuilder<ProjectData> {
     try {
       parsedState = ProjectState.valueOf(state.replace('-', '_').toUpperCase());
     } catch (IllegalArgumentException e) {
-      throw error("state operator must be either 'active' or 'read-only'");
+      throw error("state operator must be either 'active' or 'read-only'", e);
     }
     if (parsedState == ProjectState.HIDDEN) {
       throw error("state operator must be either 'active' or 'read-only'");
diff --git a/java/com/google/gerrit/server/restapi/account/Capabilities.java b/java/com/google/gerrit/server/restapi/account/Capabilities.java
index 07b12147dc..3d719ff93e 100644
--- a/java/com/google/gerrit/server/restapi/account/Capabilities.java
+++ b/java/com/google/gerrit/server/restapi/account/Capabilities.java
@@ -75,7 +75,7 @@ public class Capabilities implements ChildCollection<AccountResource, AccountRes
       permissionBackend.absentUser(target.getAccountId()).check(perm);
       return new AccountResource.Capability(target, globalOrPluginPermissionName(perm));
     } catch (AuthException e) {
-      throw new ResourceNotFoundException(id);
+      throw new ResourceNotFoundException(id, e);
     }
   }
 
diff --git a/java/com/google/gerrit/server/restapi/account/CreateAccount.java b/java/com/google/gerrit/server/restapi/account/CreateAccount.java
index 4185f3602d..42b3daf419 100644
--- a/java/com/google/gerrit/server/restapi/account/CreateAccount.java
+++ b/java/com/google/gerrit/server/restapi/account/CreateAccount.java
@@ -159,7 +159,7 @@ public class CreateAccount
       try {
         addGroupMember(groupUuid, accountId);
       } catch (NoSuchGroupException e) {
-        throw new UnprocessableEntityException(String.format("Group %s not found", groupUuid));
+        throw new UnprocessableEntityException(String.format("Group %s not found", groupUuid), e);
       }
     }
 
diff --git a/java/com/google/gerrit/server/restapi/account/PutAgreement.java b/java/com/google/gerrit/server/restapi/account/PutAgreement.java
index 0d8a81647e..ee244d0866 100644
--- a/java/com/google/gerrit/server/restapi/account/PutAgreement.java
+++ b/java/com/google/gerrit/server/restapi/account/PutAgreement.java
@@ -96,7 +96,7 @@ public class PutAgreement implements RestModifyView<AccountResource, AgreementIn
     try {
       addMembers.addMembers(uuid, ImmutableSet.of(accountState.getAccount().getId()));
     } catch (NoSuchGroupException e) {
-      throw new ResourceConflictException("autoverify group not found");
+      throw new ResourceConflictException("autoverify group not found", e);
     }
     agreementSignup.fire(accountState, agreementName);
 
diff --git a/java/com/google/gerrit/server/restapi/account/PutUsername.java b/java/com/google/gerrit/server/restapi/account/PutUsername.java
index 856a5dbb0f..7fff626d16 100644
--- a/java/com/google/gerrit/server/restapi/account/PutUsername.java
+++ b/java/com/google/gerrit/server/restapi/account/PutUsername.java
@@ -116,7 +116,7 @@ public class PutUsername implements RestModifyView<AccountResource, UsernameInpu
       }
 
       // Otherwise, someone else has this identity.
-      throw new ResourceConflictException("username already used");
+      throw new ResourceConflictException("username already used", dupeErr);
     }
 
     sshKeyCache.evict(input.username);
diff --git a/java/com/google/gerrit/server/restapi/account/SshKeys.java b/java/com/google/gerrit/server/restapi/account/SshKeys.java
index 4e44c712a8..58021316ac 100644
--- a/java/com/google/gerrit/server/restapi/account/SshKeys.java
+++ b/java/com/google/gerrit/server/restapi/account/SshKeys.java
@@ -71,7 +71,7 @@ public class SshKeys implements ChildCollection<AccountResource, AccountResource
         permissionBackend.currentUser().check(GlobalPermission.MODIFY_ACCOUNT);
       } catch (AuthException e) {
         // If lacking MODIFY_ACCOUNT claim the resource does not exist.
-        throw new ResourceNotFoundException();
+        throw new ResourceNotFoundException(id, e);
       }
     }
     return parse(rsrc.getUser(), id);
@@ -87,7 +87,7 @@ public class SshKeys implements ChildCollection<AccountResource, AccountResource
       }
       return new AccountResource.SshKey(user, sshKey);
     } catch (NumberFormatException e) {
-      throw new ResourceNotFoundException(id);
+      throw new ResourceNotFoundException(id, e);
     }
   }
 
diff --git a/java/com/google/gerrit/server/restapi/account/StarredChanges.java b/java/com/google/gerrit/server/restapi/account/StarredChanges.java
index 4849698918..88ffab816a 100644
--- a/java/com/google/gerrit/server/restapi/account/StarredChanges.java
+++ b/java/com/google/gerrit/server/restapi/account/StarredChanges.java
@@ -126,10 +126,10 @@ public class StarredChanges
       try {
         change = changes.parse(TopLevelResource.INSTANCE, id);
       } catch (ResourceNotFoundException e) {
-        throw new UnprocessableEntityException(String.format("change %s not found", id.get()));
+        throw new UnprocessableEntityException(String.format("change %s not found", id.get()), e);
       } catch (OrmException | PermissionBackendException | IOException e) {
         logger.atSevere().withCause(e).log("cannot resolve change");
-        throw new UnprocessableEntityException("internal server error");
+        throw new UnprocessableEntityException("internal server error", e);
       }
 
       try {
diff --git a/java/com/google/gerrit/server/restapi/change/CherryPickChange.java b/java/com/google/gerrit/server/restapi/change/CherryPickChange.java
index cf40b3ee82..1104761dc4 100644
--- a/java/com/google/gerrit/server/restapi/change/CherryPickChange.java
+++ b/java/com/google/gerrit/server/restapi/change/CherryPickChange.java
@@ -288,7 +288,8 @@ public class CherryPickChange {
     try {
       baseObjectId = ObjectId.fromString(base);
     } catch (InvalidObjectIdException e) {
-      throw new BadRequestException(String.format("Base %s doesn't represent a valid SHA-1", base));
+      throw new BadRequestException(
+          String.format("Base %s doesn't represent a valid SHA-1", base), e);
     }
 
     RevCommit baseCommit = revWalk.parseCommit(baseObjectId);
diff --git a/java/com/google/gerrit/server/restapi/change/CreateChange.java b/java/com/google/gerrit/server/restapi/change/CreateChange.java
index fd25658cdd..565777ec50 100644
--- a/java/com/google/gerrit/server/restapi/change/CreateChange.java
+++ b/java/com/google/gerrit/server/restapi/change/CreateChange.java
@@ -223,7 +223,7 @@ public class CreateChange
         try {
           permissionBackend.currentUser().change(change).database(db).check(ChangePermission.READ);
         } catch (AuthException e) {
-          throw new UnprocessableEntityException("Read not permitted for " + input.baseChange);
+          throw new UnprocessableEntityException("Read not permitted for " + input.baseChange, e);
         }
         PatchSet ps = psUtil.current(db.get(), change);
         parentCommit = ObjectId.fromString(ps.getRevision().get());
@@ -233,7 +233,7 @@ public class CreateChange
           parentCommit = ObjectId.fromString(input.baseCommit);
         } catch (InvalidObjectIdException e) {
           throw new UnprocessableEntityException(
-              String.format("Base %s doesn't represent a valid SHA-1", input.baseCommit));
+              String.format("Base %s doesn't represent a valid SHA-1", input.baseCommit), e);
         }
         RevCommit parentRevCommit = rw.parseCommit(parentCommit);
         RevCommit destRefRevCommit = rw.parseCommit(destRef.getObjectId());
diff --git a/java/com/google/gerrit/server/restapi/change/CreateMergePatchSet.java b/java/com/google/gerrit/server/restapi/change/CreateMergePatchSet.java
index 1b85d0be36..296ca3f7bf 100644
--- a/java/com/google/gerrit/server/restapi/change/CreateMergePatchSet.java
+++ b/java/com/google/gerrit/server/restapi/change/CreateMergePatchSet.java
@@ -214,7 +214,7 @@ public class CreateMergePatchSet
     try {
       permissionBackend.currentUser().change(change).database(db).check(ChangePermission.READ);
     } catch (AuthException e) {
-      throw new UnprocessableEntityException("Read not permitted for " + baseChange);
+      throw new UnprocessableEntityException("Read not permitted for " + baseChange, e);
     }
     return psUtil.current(db.get(), change);
   }
diff --git a/java/com/google/gerrit/server/restapi/change/GetDiff.java b/java/com/google/gerrit/server/restapi/change/GetDiff.java
index 1fae7391ae..5590da9a3a 100644
--- a/java/com/google/gerrit/server/restapi/change/GetDiff.java
+++ b/java/com/google/gerrit/server/restapi/change/GetDiff.java
@@ -22,6 +22,7 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.common.data.PatchScript;
 import com.google.gerrit.common.data.PatchScript.DisplayMethod;
 import com.google.gerrit.extensions.client.DiffPreferencesInfo;
@@ -74,6 +75,8 @@ import org.kohsuke.args4j.spi.Parameters;
 import org.kohsuke.args4j.spi.Setter;
 
 public class GetDiff implements RestReadView<FileResource> {
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
   private static final ImmutableMap<Patch.ChangeType, ChangeType> CHANGE_TYPE =
       Maps.immutableEnumMap(
           new ImmutableMap.Builder<Patch.ChangeType, ChangeType>()
@@ -439,6 +442,7 @@ public class GetDiff implements RestReadView<FileResource> {
             throw new NumberFormatException();
           }
         } catch (NumberFormatException e) {
+          logger.atFine().withCause(e).log("invalid numeric value");
           throw new CmdLineException(
               owner,
               localizable("\"%s\" is not a valid value for \"%s\""),
diff --git a/java/com/google/gerrit/server/restapi/change/PostReview.java b/java/com/google/gerrit/server/restapi/change/PostReview.java
index 845f584578..4867dd290f 100644
--- a/java/com/google/gerrit/server/restapi/change/PostReview.java
+++ b/java/com/google/gerrit/server/restapi/change/PostReview.java
@@ -497,7 +497,8 @@ public class PostReview
           throw new AuthException(
               String.format(
                   "not permitted to modify label \"%s\" on behalf of \"%s\"",
-                  type.getName(), in.onBehalfOf));
+                  type.getName(), in.onBehalfOf),
+              e);
         }
       }
     }
@@ -515,7 +516,7 @@ public class PostReview
           .check(ChangePermission.READ);
     } catch (AuthException e) {
       throw new UnprocessableEntityException(
-          String.format("on_behalf_of account %s cannot see change", reviewer.getAccountId()));
+          String.format("on_behalf_of account %s cannot see change", reviewer.getAccountId()), e);
     }
 
     return new RevisionResource(
@@ -558,7 +559,7 @@ public class PostReview
         perm.check(new LabelPermission.WithValue(lt, val));
       } catch (AuthException e) {
         throw new AuthException(
-            String.format("Applying label \"%s\": %d is restricted", lt.getName(), val));
+            String.format("Applying label \"%s\": %d is restricted", lt.getName(), val), e);
       }
     }
   }
diff --git a/java/com/google/gerrit/server/restapi/change/PreviewSubmit.java b/java/com/google/gerrit/server/restapi/change/PreviewSubmit.java
index 18e86d1a1f..c0c434c087 100644
--- a/java/com/google/gerrit/server/restapi/change/PreviewSubmit.java
+++ b/java/com/google/gerrit/server/restapi/change/PreviewSubmit.java
@@ -180,7 +180,7 @@ public class PreviewSubmit implements RestReadView<RevisionResource> {
           archiveFormat.putEntry(aos, path, bos.toByteArray());
         }
       } catch (LimitExceededException e) {
-        throw new NotImplementedException("The bundle is too big to generate at the server");
+        throw new NotImplementedException("The bundle is too big to generate at the server", e);
       } catch (NoSuchProjectException e) {
         throw new IOException(e);
       }
diff --git a/java/com/google/gerrit/server/restapi/change/PutAssignee.java b/java/com/google/gerrit/server/restapi/change/PutAssignee.java
index 7878ce5fe9..d247d5ed75 100644
--- a/java/com/google/gerrit/server/restapi/change/PutAssignee.java
+++ b/java/com/google/gerrit/server/restapi/change/PutAssignee.java
@@ -100,7 +100,7 @@ public class PutAssignee extends RetryingRestModifyView<ChangeResource, Assignee
           .change(rsrc.getNotes())
           .check(ChangePermission.READ);
     } catch (AuthException e) {
-      throw new AuthException("read not permitted for " + input.assignee);
+      throw new AuthException("read not permitted for " + input.assignee, e);
     }
 
     try (BatchUpdate bu =
diff --git a/java/com/google/gerrit/server/restapi/change/QueryChanges.java b/java/com/google/gerrit/server/restapi/change/QueryChanges.java
index d1eea44884..082d27de8d 100644
--- a/java/com/google/gerrit/server/restapi/change/QueryChanges.java
+++ b/java/com/google/gerrit/server/restapi/change/QueryChanges.java
@@ -114,7 +114,7 @@ public class QueryChanges implements RestReadView<TopLevelResource>, DynamicOpti
     try {
       out = query();
     } catch (QueryRequiresAuthException e) {
-      throw new AuthException("Must be signed-in to use this operator");
+      throw new AuthException("Must be signed-in to use this operator", e);
     } catch (QueryParseException e) {
       logger.atFine().withCause(e).log("Reject change query with 400 Bad Request: %s", queries);
       throw new BadRequestException(e.getMessage(), e);
diff --git a/java/com/google/gerrit/server/restapi/change/Rebuild.java b/java/com/google/gerrit/server/restapi/change/Rebuild.java
index dc390ccae3..ec17598789 100644
--- a/java/com/google/gerrit/server/restapi/change/Rebuild.java
+++ b/java/com/google/gerrit/server/restapi/change/Rebuild.java
@@ -103,7 +103,7 @@ public class Rebuild implements RestModifyView<ChangeResource, Input> {
     try {
       rebuilder.rebuild(db.get(), rsrc.getId());
     } catch (NoSuchChangeException e) {
-      throw new ResourceNotFoundException(IdString.fromDecoded(rsrc.getId().toString()));
+      throw new ResourceNotFoundException(IdString.fromDecoded(rsrc.getId().toString()), e);
     }
   }
 }
diff --git a/java/com/google/gerrit/server/restapi/change/Submit.java b/java/com/google/gerrit/server/restapi/change/Submit.java
index 7c1011744d..a775c9399f 100644
--- a/java/com/google/gerrit/server/restapi/change/Submit.java
+++ b/java/com/google/gerrit/server/restapi/change/Submit.java
@@ -218,7 +218,7 @@ public class Submit
         change =
             changeNotesFactory.createChecked(db, change.getProject(), change.getId()).getChange();
       } catch (NoSuchChangeException e) {
-        throw new ResourceConflictException("change is deleted");
+        throw new ResourceConflictException("change is deleted", e);
       }
     }
 
@@ -473,7 +473,7 @@ public class Submit
           .check(ChangePermission.READ);
     } catch (AuthException e) {
       throw new UnprocessableEntityException(
-          String.format("on_behalf_of account %s cannot see change", submitter.getAccountId()));
+          String.format("on_behalf_of account %s cannot see change", submitter.getAccountId()), e);
     }
     return submitter;
   }
diff --git a/java/com/google/gerrit/server/restapi/config/ConfirmEmail.java b/java/com/google/gerrit/server/restapi/config/ConfirmEmail.java
index 5a1592f01f..d16a379005 100644
--- a/java/com/google/gerrit/server/restapi/config/ConfirmEmail.java
+++ b/java/com/google/gerrit/server/restapi/config/ConfirmEmail.java
@@ -78,7 +78,7 @@ public class ConfirmEmail implements RestModifyView<ConfigResource, Input> {
       }
       throw new UnprocessableEntityException("invalid token");
     } catch (EmailTokenVerifier.InvalidTokenException e) {
-      throw new UnprocessableEntityException("invalid token");
+      throw new UnprocessableEntityException("invalid token", e);
     } catch (AccountException e) {
       throw new UnprocessableEntityException(e.getMessage());
     }
diff --git a/java/com/google/gerrit/server/restapi/config/TasksCollection.java b/java/com/google/gerrit/server/restapi/config/TasksCollection.java
index dda54a0a62..9a7aa3a3dd 100644
--- a/java/com/google/gerrit/server/restapi/config/TasksCollection.java
+++ b/java/com/google/gerrit/server/restapi/config/TasksCollection.java
@@ -81,7 +81,7 @@ public class TasksCollection implements ChildCollection<ConfigResource, TaskReso
     try {
       taskId = (int) Long.parseLong(id.get(), 16);
     } catch (NumberFormatException e) {
-      throw new ResourceNotFoundException(id);
+      throw new ResourceNotFoundException(id, e);
     }
 
     Task<?> task = workQueue.getTask(taskId);
diff --git a/java/com/google/gerrit/server/restapi/group/AddMembers.java b/java/com/google/gerrit/server/restapi/group/AddMembers.java
index bdf1c74f04..52835180b2 100644
--- a/java/com/google/gerrit/server/restapi/group/AddMembers.java
+++ b/java/com/google/gerrit/server/restapi/group/AddMembers.java
@@ -138,7 +138,7 @@ public class AddMembers implements RestModifyView<GroupResource, Input> {
     try {
       addMembers(groupUuid, newMemberIds);
     } catch (NoSuchGroupException e) {
-      throw new ResourceNotFoundException(String.format("Group %s not found", groupUuid));
+      throw new ResourceNotFoundException(String.format("Group %s not found", groupUuid), e);
     }
     return toAccountInfoList(newMemberIds);
   }
@@ -235,7 +235,7 @@ public class AddMembers implements RestModifyView<GroupResource, Input> {
         }
         throw new IllegalStateException();
       } catch (UnprocessableEntityException e) {
-        throw new ResourceNotFoundException(id);
+        throw new ResourceNotFoundException(id, e);
       }
     }
   }
diff --git a/java/com/google/gerrit/server/restapi/group/AddSubgroups.java b/java/com/google/gerrit/server/restapi/group/AddSubgroups.java
index 9782ad3ecf..02c4a290c2 100644
--- a/java/com/google/gerrit/server/restapi/group/AddSubgroups.java
+++ b/java/com/google/gerrit/server/restapi/group/AddSubgroups.java
@@ -117,7 +117,7 @@ public class AddSubgroups implements RestModifyView<GroupResource, Input> {
     try {
       addSubgroups(groupUuid, subgroupUuids);
     } catch (NoSuchGroupException e) {
-      throw new ResourceNotFoundException(String.format("Group %s not found", groupUuid));
+      throw new ResourceNotFoundException(String.format("Group %s not found", groupUuid), e);
     }
     return result;
   }
@@ -155,7 +155,7 @@ public class AddSubgroups implements RestModifyView<GroupResource, Input> {
         }
         throw new IllegalStateException();
       } catch (UnprocessableEntityException e) {
-        throw new ResourceNotFoundException(id);
+        throw new ResourceNotFoundException(id, e);
       }
     }
   }
diff --git a/java/com/google/gerrit/server/restapi/group/CreateGroup.java b/java/com/google/gerrit/server/restapi/group/CreateGroup.java
index 05721146b2..4a2375b6bc 100644
--- a/java/com/google/gerrit/server/restapi/group/CreateGroup.java
+++ b/java/com/google/gerrit/server/restapi/group/CreateGroup.java
@@ -220,7 +220,7 @@ public class CreateGroup
       return groupsUpdateProvider.get().createGroup(groupCreation, groupUpdateBuilder.build());
     } catch (OrmDuplicateKeyException e) {
       throw new ResourceConflictException(
-          "group '" + createGroupArgs.getGroupName() + "' already exists");
+          "group '" + createGroupArgs.getGroupName() + "' already exists", e);
     }
   }
 }
diff --git a/java/com/google/gerrit/server/restapi/group/DeleteMembers.java b/java/com/google/gerrit/server/restapi/group/DeleteMembers.java
index d197cb844b..82dc7d9ac7 100644
--- a/java/com/google/gerrit/server/restapi/group/DeleteMembers.java
+++ b/java/com/google/gerrit/server/restapi/group/DeleteMembers.java
@@ -76,7 +76,7 @@ public class DeleteMembers implements RestModifyView<GroupResource, Input> {
     try {
       removeGroupMembers(groupUuid, membersToRemove);
     } catch (NoSuchGroupException e) {
-      throw new ResourceNotFoundException(String.format("Group %s not found", groupUuid));
+      throw new ResourceNotFoundException(String.format("Group %s not found", groupUuid), e);
     }
 
     return Response.none();
diff --git a/java/com/google/gerrit/server/restapi/group/DeleteSubgroups.java b/java/com/google/gerrit/server/restapi/group/DeleteSubgroups.java
index c486af402f..307f874a72 100644
--- a/java/com/google/gerrit/server/restapi/group/DeleteSubgroups.java
+++ b/java/com/google/gerrit/server/restapi/group/DeleteSubgroups.java
@@ -78,7 +78,7 @@ public class DeleteSubgroups implements RestModifyView<GroupResource, Input> {
     try {
       removeSubgroups(groupUuid, subgroupsToRemove);
     } catch (NoSuchGroupException e) {
-      throw new ResourceNotFoundException(String.format("Group %s not found", groupUuid));
+      throw new ResourceNotFoundException(String.format("Group %s not found", groupUuid), e);
     }
 
     return Response.none();
diff --git a/java/com/google/gerrit/server/restapi/group/GetOwner.java b/java/com/google/gerrit/server/restapi/group/GetOwner.java
index 0906ce6b7f..6a97d01c15 100644
--- a/java/com/google/gerrit/server/restapi/group/GetOwner.java
+++ b/java/com/google/gerrit/server/restapi/group/GetOwner.java
@@ -48,7 +48,7 @@ public class GetOwner implements RestReadView<GroupResource> {
       GroupControl c = controlFactory.validateFor(group.getOwnerGroupUUID());
       return json.format(c.getGroup());
     } catch (NoSuchGroupException e) {
-      throw new ResourceNotFoundException();
+      throw new ResourceNotFoundException(group.getOwnerGroupUUID().get(), e);
     }
   }
 }
diff --git a/java/com/google/gerrit/server/restapi/group/PutDescription.java b/java/com/google/gerrit/server/restapi/group/PutDescription.java
index d407f69d17..9ce180f4c3 100644
--- a/java/com/google/gerrit/server/restapi/group/PutDescription.java
+++ b/java/com/google/gerrit/server/restapi/group/PutDescription.java
@@ -67,7 +67,7 @@ public class PutDescription implements RestModifyView<GroupResource, Description
       try {
         groupsUpdateProvider.get().updateGroup(groupUuid, groupUpdate);
       } catch (NoSuchGroupException e) {
-        throw new ResourceNotFoundException(String.format("Group %s not found", groupUuid));
+        throw new ResourceNotFoundException(String.format("Group %s not found", groupUuid), e);
       }
     }
 
diff --git a/java/com/google/gerrit/server/restapi/group/PutName.java b/java/com/google/gerrit/server/restapi/group/PutName.java
index 1f1968a675..83757d01ec 100644
--- a/java/com/google/gerrit/server/restapi/group/PutName.java
+++ b/java/com/google/gerrit/server/restapi/group/PutName.java
@@ -78,9 +78,9 @@ public class PutName implements RestModifyView<GroupResource, NameInput> {
     try {
       groupsUpdateProvider.get().updateGroup(groupUuid, groupUpdate);
     } catch (NoSuchGroupException e) {
-      throw new ResourceNotFoundException(String.format("Group %s not found", groupUuid));
+      throw new ResourceNotFoundException(String.format("Group %s not found", groupUuid), e);
     } catch (OrmDuplicateKeyException e) {
-      throw new ResourceConflictException("group with name " + newName + " already exists");
+      throw new ResourceConflictException("group with name " + newName + " already exists", e);
     }
   }
 }
diff --git a/java/com/google/gerrit/server/restapi/group/PutOptions.java b/java/com/google/gerrit/server/restapi/group/PutOptions.java
index 29b87d2015..8698ee6da3 100644
--- a/java/com/google/gerrit/server/restapi/group/PutOptions.java
+++ b/java/com/google/gerrit/server/restapi/group/PutOptions.java
@@ -66,7 +66,7 @@ public class PutOptions implements RestModifyView<GroupResource, GroupOptionsInf
       try {
         groupsUpdateProvider.get().updateGroup(groupUuid, groupUpdate);
       } catch (NoSuchGroupException e) {
-        throw new ResourceNotFoundException(String.format("Group %s not found", groupUuid));
+        throw new ResourceNotFoundException(String.format("Group %s not found", groupUuid), e);
       }
     }
 
diff --git a/java/com/google/gerrit/server/restapi/group/PutOwner.java b/java/com/google/gerrit/server/restapi/group/PutOwner.java
index 6ebec0598c..0b007daa7d 100644
--- a/java/com/google/gerrit/server/restapi/group/PutOwner.java
+++ b/java/com/google/gerrit/server/restapi/group/PutOwner.java
@@ -77,7 +77,7 @@ public class PutOwner implements RestModifyView<GroupResource, OwnerInput> {
       try {
         groupsUpdateProvider.get().updateGroup(groupUuid, groupUpdate);
       } catch (NoSuchGroupException e) {
-        throw new ResourceNotFoundException(String.format("Group %s not found", groupUuid));
+        throw new ResourceNotFoundException(String.format("Group %s not found", groupUuid), e);
       }
     }
     return json.format(owner);
diff --git a/java/com/google/gerrit/server/restapi/project/BranchesCollection.java b/java/com/google/gerrit/server/restapi/project/BranchesCollection.java
index 2b7e08960d..5fbb4f8b35 100644
--- a/java/com/google/gerrit/server/restapi/project/BranchesCollection.java
+++ b/java/com/google/gerrit/server/restapi/project/BranchesCollection.java
@@ -82,9 +82,9 @@ public class BranchesCollection implements ChildCollection<ProjectResource, Bran
           .check(RefPermission.READ);
       return new BranchResource(parent.getProjectState(), parent.getUser(), ref);
     } catch (AuthException notAllowed) {
-      throw new ResourceNotFoundException(id);
+      throw new ResourceNotFoundException(id, notAllowed);
     } catch (RepositoryNotFoundException noRepo) {
-      throw new ResourceNotFoundException();
+      throw new ResourceNotFoundException(id, noRepo);
     }
   }
 
diff --git a/java/com/google/gerrit/server/restapi/project/CommitsCollection.java b/java/com/google/gerrit/server/restapi/project/CommitsCollection.java
index 15cd824a57..dc53923dd1 100644
--- a/java/com/google/gerrit/server/restapi/project/CommitsCollection.java
+++ b/java/com/google/gerrit/server/restapi/project/CommitsCollection.java
@@ -80,7 +80,7 @@ public class CommitsCollection implements ChildCollection<ProjectResource, Commi
     try {
       objectId = ObjectId.fromString(id.get());
     } catch (IllegalArgumentException e) {
-      throw new ResourceNotFoundException(id);
+      throw new ResourceNotFoundException(id, e);
     }
 
     try (Repository repo = repoManager.openRepository(parent.getNameKey());
@@ -95,7 +95,7 @@ public class CommitsCollection implements ChildCollection<ProjectResource, Commi
       }
       return new CommitResource(parent, commit);
     } catch (MissingObjectException | IncorrectObjectTypeException e) {
-      throw new ResourceNotFoundException(id);
+      throw new ResourceNotFoundException(id, e);
     }
   }
 
diff --git a/java/com/google/gerrit/server/restapi/project/CreateAccessChange.java b/java/com/google/gerrit/server/restapi/project/CreateAccessChange.java
index feb37c09fe..66a8de2edd 100644
--- a/java/com/google/gerrit/server/restapi/project/CreateAccessChange.java
+++ b/java/com/google/gerrit/server/restapi/project/CreateAccessChange.java
@@ -104,7 +104,7 @@ public class CreateAccessChange implements RestModifyView<ProjectResource, Proje
       try {
         forProject.ref(RefNames.REFS_CONFIG).check(RefPermission.CREATE_CHANGE);
       } catch (AuthException denied) {
-        throw new AuthException("cannot create change for " + RefNames.REFS_CONFIG);
+        throw new AuthException("cannot create change for " + RefNames.REFS_CONFIG, denied);
       }
     }
     projectCache.checkedGet(rsrc.getNameKey()).checkStatePermitsWrite();
diff --git a/java/com/google/gerrit/server/restapi/project/CreateBranch.java b/java/com/google/gerrit/server/restapi/project/CreateBranch.java
index ec1f56e718..01e0cdfc41 100644
--- a/java/com/google/gerrit/server/restapi/project/CreateBranch.java
+++ b/java/com/google/gerrit/server/restapi/project/CreateBranch.java
@@ -125,7 +125,7 @@ public class CreateBranch
         try {
           object = rw.parseCommit(object);
         } catch (IncorrectObjectTypeException notCommit) {
-          throw new BadRequestException("\"" + input.revision + "\" not a commit");
+          throw new BadRequestException("\"" + input.revision + "\" not a commit", notCommit);
         }
       }
 
@@ -198,7 +198,7 @@ public class CreateBranch
         throw err;
       }
     } catch (RefUtil.InvalidRevisionException e) {
-      throw new BadRequestException("invalid revision \"" + input.revision + "\"");
+      throw new BadRequestException("invalid revision \"" + input.revision + "\"", e);
     }
   }
 }
diff --git a/java/com/google/gerrit/server/restapi/project/CreateProject.java b/java/com/google/gerrit/server/restapi/project/CreateProject.java
index 74b185d7f9..eacce18c86 100644
--- a/java/com/google/gerrit/server/restapi/project/CreateProject.java
+++ b/java/com/google/gerrit/server/restapi/project/CreateProject.java
@@ -275,9 +275,10 @@ public class CreateProject
               + nameKey.get()
               + " because the name is already occupied by another project."
               + " The other project has the same name, only spelled in a"
-              + " different case.");
+              + " different case.",
+          e);
     } catch (RepositoryNotFoundException badName) {
-      throw new BadRequestException("invalid project name: " + nameKey);
+      throw new BadRequestException("invalid project name: " + nameKey, badName);
     } catch (ConfigInvalidException e) {
       String msg = "Cannot create " + nameKey;
       logger.atSevere().withCause(e).log(msg);
diff --git a/java/com/google/gerrit/server/restapi/project/CreateTag.java b/java/com/google/gerrit/server/restapi/project/CreateTag.java
index 855a7c7429..7493d244ba 100644
--- a/java/com/google/gerrit/server/restapi/project/CreateTag.java
+++ b/java/com/google/gerrit/server/restapi/project/CreateTag.java
@@ -147,7 +147,7 @@ public class CreateTag implements RestCollectionCreateView<ProjectResource, TagR
         }
       }
     } catch (InvalidRevisionException e) {
-      throw new BadRequestException("Invalid base revision");
+      throw new BadRequestException("Invalid base revision", e);
     } catch (GitAPIException e) {
       logger.atSevere().withCause(e).log("Cannot create tag \"%s\"", ref);
       throw new IOException(e);
diff --git a/java/com/google/gerrit/server/restapi/project/DashboardsCollection.java b/java/com/google/gerrit/server/restapi/project/DashboardsCollection.java
index 07691e7251..4dc83e87c1 100644
--- a/java/com/google/gerrit/server/restapi/project/DashboardsCollection.java
+++ b/java/com/google/gerrit/server/restapi/project/DashboardsCollection.java
@@ -103,14 +103,14 @@ public class DashboardsCollection implements ChildCollection<ProjectResource, Da
     try {
       info = newDashboardInfo(id.get());
     } catch (InvalidDashboardId e) {
-      throw new ResourceNotFoundException(id);
+      throw new ResourceNotFoundException(id, e);
     }
 
     for (ProjectState ps : parent.getProjectState().tree()) {
       try {
         return parse(ps, parent.getProjectState(), parent.getUser(), info);
       } catch (AmbiguousObjectException | ConfigInvalidException | IncorrectObjectTypeException e) {
-        throw new ResourceNotFoundException(id);
+        throw new ResourceNotFoundException(id, e);
       } catch (ResourceNotFoundException e) {
         continue;
       }
@@ -135,7 +135,7 @@ public class DashboardsCollection implements ChildCollection<ProjectResource, Da
       permissionBackend.user(user).project(parent.getNameKey()).ref(ref).check(RefPermission.READ);
     } catch (AuthException e) {
       // Don't leak the project's existence
-      throw new ResourceNotFoundException(info.id);
+      throw new ResourceNotFoundException(info.id, e);
     }
     if (!Repository.isValidRefName(ref)) {
       throw new ResourceNotFoundException(info.id);
@@ -151,7 +151,7 @@ public class DashboardsCollection implements ChildCollection<ProjectResource, Da
       BlobBasedConfig cfg = new BlobBasedConfig(null, git, objId);
       return new DashboardResource(current, user, ref, info.path, cfg, false);
     } catch (RepositoryNotFoundException e) {
-      throw new ResourceNotFoundException(info.id);
+      throw new ResourceNotFoundException(info.id, e);
     }
   }
 
diff --git a/java/com/google/gerrit/server/restapi/project/GetAccess.java b/java/com/google/gerrit/server/restapi/project/GetAccess.java
index 7862ff5300..4ec187a68e 100644
--- a/java/com/google/gerrit/server/restapi/project/GetAccess.java
+++ b/java/com/google/gerrit/server/restapi/project/GetAccess.java
@@ -170,7 +170,7 @@ public class GetAccess implements RestReadView<ProjectResource> {
     } catch (ConfigInvalidException e) {
       throw new ResourceConflictException(e.getMessage());
     } catch (RepositoryNotFoundException e) {
-      throw new ResourceNotFoundException(rsrc.getName());
+      throw new ResourceNotFoundException(rsrc.getName(), e);
     }
 
     // The following implementation must match the ProjectAccessFactory JSON RPC endpoint.
diff --git a/java/com/google/gerrit/server/restapi/project/GetHead.java b/java/com/google/gerrit/server/restapi/project/GetHead.java
index bc267c8525..043991fc59 100644
--- a/java/com/google/gerrit/server/restapi/project/GetHead.java
+++ b/java/com/google/gerrit/server/restapi/project/GetHead.java
@@ -81,13 +81,13 @@ public class GetHead implements RestReadView<ProjectResource> {
                 .project(rsrc.getNameKey())
                 .check(ProjectPermission.WRITE_CONFIG);
           } catch (AuthException ae) {
-            throw new AuthException("not allowed to see HEAD");
+            throw new AuthException("not allowed to see HEAD", ae);
           }
         }
       }
       throw new ResourceNotFoundException(Constants.HEAD);
     } catch (RepositoryNotFoundException e) {
-      throw new ResourceNotFoundException(rsrc.getName());
+      throw new ResourceNotFoundException(rsrc.getName(), e);
     }
   }
 }
diff --git a/java/com/google/gerrit/server/restapi/project/GetReflog.java b/java/com/google/gerrit/server/restapi/project/GetReflog.java
index 4b9a489d81..a690042186 100644
--- a/java/com/google/gerrit/server/restapi/project/GetReflog.java
+++ b/java/com/google/gerrit/server/restapi/project/GetReflog.java
@@ -103,7 +103,7 @@ public class GetReflog implements RestReadView<BranchResource> {
       } catch (UnsupportedOperationException e) {
         String msg = "reflog not supported on repo " + rsrc.getNameKey().get();
         logger.atSevere().log(msg);
-        throw new MethodNotAllowedException(msg);
+        throw new MethodNotAllowedException(msg, e);
       }
       if (r == null) {
         throw new ResourceNotFoundException(rsrc.getRef());
diff --git a/java/com/google/gerrit/server/restapi/project/GetStatistics.java b/java/com/google/gerrit/server/restapi/project/GetStatistics.java
index 048c018b9f..a40806227e 100644
--- a/java/com/google/gerrit/server/restapi/project/GetStatistics.java
+++ b/java/com/google/gerrit/server/restapi/project/GetStatistics.java
@@ -50,7 +50,7 @@ public class GetStatistics implements RestReadView<ProjectResource> {
     } catch (GitAPIException | JGitInternalException e) {
       throw new ResourceConflictException(e.getMessage());
     } catch (IOException e) {
-      throw new ResourceNotFoundException(rsrc.getName());
+      throw new ResourceNotFoundException(rsrc.getName(), e);
     }
   }
 }
diff --git a/java/com/google/gerrit/server/restapi/project/ListBranches.java b/java/com/google/gerrit/server/restapi/project/ListBranches.java
index a0d2528ed0..ae9ef28d2b 100644
--- a/java/com/google/gerrit/server/restapi/project/ListBranches.java
+++ b/java/com/google/gerrit/server/restapi/project/ListBranches.java
@@ -147,7 +147,7 @@ public class ListBranches implements RestReadView<ProjectResource> {
       }
       return toBranchInfo(rsrc, ImmutableList.of(r)).get(0);
     } catch (RepositoryNotFoundException noRepo) {
-      throw new ResourceNotFoundException();
+      throw new ResourceNotFoundException(rsrc.getNameKey().get(), noRepo);
     }
   }
 
@@ -163,7 +163,7 @@ public class ListBranches implements RestReadView<ProjectResource> {
               .exactRef(Constants.HEAD, RefNames.REFS_CONFIG, RefNames.REFS_USERS_DEFAULT)
               .values());
     } catch (RepositoryNotFoundException noGitRepository) {
-      throw new ResourceNotFoundException();
+      throw new ResourceNotFoundException(rsrc.getNameKey().get(), noGitRepository);
     }
     return toBranchInfo(rsrc, refs);
   }
diff --git a/java/com/google/gerrit/server/restapi/project/ListDashboards.java b/java/com/google/gerrit/server/restapi/project/ListDashboards.java
index 3808a2f798..fd8668ad10 100644
--- a/java/com/google/gerrit/server/restapi/project/ListDashboards.java
+++ b/java/com/google/gerrit/server/restapi/project/ListDashboards.java
@@ -119,7 +119,7 @@ public class ListDashboards implements RestReadView<ProjectResource> {
       }
       return all;
     } catch (RepositoryNotFoundException e) {
-      throw new ResourceNotFoundException();
+      throw new ResourceNotFoundException(project, e);
     }
   }
 
diff --git a/java/com/google/gerrit/server/restapi/project/ListTags.java b/java/com/google/gerrit/server/restapi/project/ListTags.java
index f59e98421c..5fbfcf6f83 100644
--- a/java/com/google/gerrit/server/restapi/project/ListTags.java
+++ b/java/com/google/gerrit/server/restapi/project/ListTags.java
@@ -217,7 +217,7 @@ public class ListTags implements RestReadView<ProjectResource> {
     try {
       return repoManager.openRepository(project);
     } catch (RepositoryNotFoundException noGitRepository) {
-      throw new ResourceNotFoundException();
+      throw new ResourceNotFoundException(project.get(), noGitRepository);
     }
   }
 
diff --git a/java/com/google/gerrit/server/restapi/project/PutConfig.java b/java/com/google/gerrit/server/restapi/project/PutConfig.java
index 76ea0c9125..e0b443b211 100644
--- a/java/com/google/gerrit/server/restapi/project/PutConfig.java
+++ b/java/com/google/gerrit/server/restapi/project/PutConfig.java
@@ -175,7 +175,7 @@ public class PutConfig implements RestModifyView<ProjectResource, ConfigInput> {
           uiActions,
           views);
     } catch (RepositoryNotFoundException notFound) {
-      throw new ResourceNotFoundException(projectName.get());
+      throw new ResourceNotFoundException(projectName.get(), notFound);
     } catch (ConfigInvalidException err) {
       throw new ResourceConflictException("Cannot read project " + projectName, err);
     } catch (IOException err) {
diff --git a/java/com/google/gerrit/server/restapi/project/PutDescription.java b/java/com/google/gerrit/server/restapi/project/PutDescription.java
index 039b65bc6d..f3366e5324 100644
--- a/java/com/google/gerrit/server/restapi/project/PutDescription.java
+++ b/java/com/google/gerrit/server/restapi/project/PutDescription.java
@@ -89,7 +89,7 @@ public class PutDescription implements RestModifyView<ProjectResource, Descripti
           ? Response.<String>none()
           : Response.ok(project.getDescription());
     } catch (RepositoryNotFoundException notFound) {
-      throw new ResourceNotFoundException(resource.getName());
+      throw new ResourceNotFoundException(resource.getName(), notFound);
     } catch (ConfigInvalidException e) {
       throw new ResourceConflictException(
           String.format("invalid project.config: %s", e.getMessage()));
diff --git a/java/com/google/gerrit/server/restapi/project/SetAccess.java b/java/com/google/gerrit/server/restapi/project/SetAccess.java
index c9d69a5141..4cefa4bddb 100644
--- a/java/com/google/gerrit/server/restapi/project/SetAccess.java
+++ b/java/com/google/gerrit/server/restapi/project/SetAccess.java
@@ -134,7 +134,7 @@ public class SetAccess implements RestModifyView<ProjectResource, ProjectAccessI
     } catch (InvalidNameException e) {
       throw new BadRequestException(e.toString());
     } catch (ConfigInvalidException e) {
-      throw new ResourceConflictException(rsrc.getName());
+      throw new ResourceConflictException(rsrc.getName(), e);
     }
 
     return getAccess.apply(rsrc.getNameKey());
diff --git a/java/com/google/gerrit/server/restapi/project/SetDefaultDashboard.java b/java/com/google/gerrit/server/restapi/project/SetDefaultDashboard.java
index ef292e5c8f..374f3b9e8e 100644
--- a/java/com/google/gerrit/server/restapi/project/SetDefaultDashboard.java
+++ b/java/com/google/gerrit/server/restapi/project/SetDefaultDashboard.java
@@ -86,7 +86,7 @@ class SetDefaultDashboard implements RestModifyView<DashboardResource, SetDashbo
                 new ProjectResource(rsrc.getProjectState(), rsrc.getUser()),
                 IdString.fromUrl(input.id));
       } catch (ResourceNotFoundException e) {
-        throw new BadRequestException("dashboard " + input.id + " not found");
+        throw new BadRequestException("dashboard " + input.id + " not found", e);
       } catch (ConfigInvalidException e) {
         throw new ResourceConflictException(e.getMessage());
       }
@@ -122,7 +122,7 @@ class SetDefaultDashboard implements RestModifyView<DashboardResource, SetDashbo
       }
       return Response.none();
     } catch (RepositoryNotFoundException notFound) {
-      throw new ResourceNotFoundException(rsrc.getProjectState().getProject().getName());
+      throw new ResourceNotFoundException(rsrc.getProjectState().getProject().getName(), notFound);
     } catch (ConfigInvalidException e) {
       throw new ResourceConflictException(
           String.format("invalid project.config: %s", e.getMessage()));
diff --git a/java/com/google/gerrit/server/restapi/project/SetHead.java b/java/com/google/gerrit/server/restapi/project/SetHead.java
index b310f16f54..430d709888 100644
--- a/java/com/google/gerrit/server/restapi/project/SetHead.java
+++ b/java/com/google/gerrit/server/restapi/project/SetHead.java
@@ -111,7 +111,7 @@ public class SetHead implements RestModifyView<ProjectResource, HeadInput> {
       }
       return ref;
     } catch (RepositoryNotFoundException e) {
-      throw new ResourceNotFoundException(rsrc.getName());
+      throw new ResourceNotFoundException(rsrc.getName(), e);
     }
   }
 
diff --git a/java/com/google/gerrit/server/restapi/project/SetParent.java b/java/com/google/gerrit/server/restapi/project/SetParent.java
index 61d5622492..134a74e575 100644
--- a/java/com/google/gerrit/server/restapi/project/SetParent.java
+++ b/java/com/google/gerrit/server/restapi/project/SetParent.java
@@ -117,7 +117,7 @@ public class SetParent
       requireNonNull(parent);
       return parent.get();
     } catch (RepositoryNotFoundException notFound) {
-      throw new ResourceNotFoundException(rsrc.getName());
+      throw new ResourceNotFoundException(rsrc.getName(), notFound);
     } catch (ConfigInvalidException e) {
       throw new ResourceConflictException(
           String.format("invalid project.config: %s", e.getMessage()));
diff --git a/java/com/google/gerrit/server/rules/StoredValues.java b/java/com/google/gerrit/server/rules/StoredValues.java
index 8b9cfe3fdb..ed70629937 100644
--- a/java/com/google/gerrit/server/rules/StoredValues.java
+++ b/java/com/google/gerrit/server/rules/StoredValues.java
@@ -59,7 +59,8 @@ public final class StoredValues {
     try {
       return cd.change();
     } catch (OrmException e) {
-      throw new SystemException("Cannot load change " + cd.getId());
+      throw new SystemException(
+          String.format("Cannot load change %s: %s", cd.getId(), e.getMessage()));
     }
   }
 
@@ -104,7 +105,7 @@ public final class StoredValues {
           try {
             patchList = plCache.get(plKey, project);
           } catch (PatchListNotAvailableException e) {
-            throw new SystemException("Cannot create " + plKey);
+            throw new SystemException(String.format("Cannot create %s: %s", plKey, e.getMessage()));
           }
           return patchList;
         }
diff --git a/java/com/google/gerrit/server/schema/Schema_106.java b/java/com/google/gerrit/server/schema/Schema_106.java
index 5bb3669a14..7b6a30a8b2 100644
--- a/java/com/google/gerrit/server/schema/Schema_106.java
+++ b/java/com/google/gerrit/server/schema/Schema_106.java
@@ -152,7 +152,8 @@ public class Schema_106 extends SchemaVersion {
         throw new IOException(
             String.format(
                 "ERROR: Failed to create reflog file for the %s branch in repository %s",
-                RefNames.REFS_CONFIG, project.get()));
+                RefNames.REFS_CONFIG, project.get()),
+            e);
       }
     }
   }
diff --git a/java/com/google/gerrit/server/submit/RebaseSubmitStrategy.java b/java/com/google/gerrit/server/submit/RebaseSubmitStrategy.java
index cf3a44e0d8..1ec7ca853a 100644
--- a/java/com/google/gerrit/server/submit/RebaseSubmitStrategy.java
+++ b/java/com/google/gerrit/server/submit/RebaseSubmitStrategy.java
@@ -161,7 +161,8 @@ public class RebaseSubmitStrategy extends SubmitStrategy {
         } catch (MergeConflictException mce) {
           // Unlike in Cherry-pick case, this should never happen.
           toMerge.setStatusCode(CommitMergeStatus.REBASE_MERGE_CONFLICT);
-          throw new IllegalStateException("MergeConflictException on message edit must not happen");
+          throw new IllegalStateException(
+              "MergeConflictException on message edit must not happen", mce);
         } catch (MergeIdenticalTreeException mie) {
           // this should not happen
           toMerge.setStatusCode(SKIPPED_IDENTICAL_TREE);
diff --git a/java/com/google/gerrit/server/submit/SubmitStrategyOp.java b/java/com/google/gerrit/server/submit/SubmitStrategyOp.java
index 8a4fbfbe5c..303c95666b 100644
--- a/java/com/google/gerrit/server/submit/SubmitStrategyOp.java
+++ b/java/com/google/gerrit/server/submit/SubmitStrategyOp.java
@@ -590,7 +590,7 @@ abstract class SubmitStrategyOp implements BatchUpdateOp {
       return args.submoduleOp.composeGitlinksCommit(args.destBranch, commit);
     } catch (SubmoduleException | IOException e) {
       throw new IntegrationException(
-          "cannot update gitlink for the commit at branch: " + args.destBranch);
+          "cannot update gitlink for the commit at branch: " + args.destBranch, e);
     }
   }
 }
diff --git a/java/com/google/gerrit/server/util/SocketUtil.java b/java/com/google/gerrit/server/util/SocketUtil.java
index afa2aee683..e617650a63 100644
--- a/java/com/google/gerrit/server/util/SocketUtil.java
+++ b/java/com/google/gerrit/server/util/SocketUtil.java
@@ -96,7 +96,7 @@ public final class SocketUtil {
       try {
         port = Integer.parseInt(portStr);
       } catch (NumberFormatException e) {
-        throw new IllegalArgumentException("invalid port: " + desc);
+        throw new IllegalArgumentException("invalid port: " + desc, e);
       }
     } else {
       port = defaultPort;
diff --git a/java/com/google/gerrit/sshd/BaseCommand.java b/java/com/google/gerrit/sshd/BaseCommand.java
index 2081967b50..472f1c7218 100644
--- a/java/com/google/gerrit/sshd/BaseCommand.java
+++ b/java/com/google/gerrit/sshd/BaseCommand.java
@@ -385,6 +385,10 @@ public abstract class BaseCommand implements Command {
     return new UnloggedFailure(1, "fatal: " + msg);
   }
 
+  protected UnloggedFailure die(String msg, Throwable why) {
+    return new UnloggedFailure(1, "fatal: " + msg, why);
+  }
+
   protected UnloggedFailure die(Throwable why) {
     return new UnloggedFailure(1, "fatal: " + why.getMessage(), why);
   }
diff --git a/java/com/google/gerrit/sshd/ChangeArgumentParser.java b/java/com/google/gerrit/sshd/ChangeArgumentParser.java
index 692884ec65..ce3b8a9e3f 100644
--- a/java/com/google/gerrit/sshd/ChangeArgumentParser.java
+++ b/java/com/google/gerrit/sshd/ChangeArgumentParser.java
@@ -116,7 +116,7 @@ public class ChangeArgumentParser {
     try {
       changeResource = changesCollection.parse(cId);
     } catch (RestApiException e) {
-      throw new UnloggedFailure(1, "\"" + id + "\" no such change");
+      throw new UnloggedFailure(1, "\"" + id + "\" no such change", e);
     }
     changes.put(cId, changeResource);
   }
diff --git a/java/com/google/gerrit/sshd/SshKeyCreatorImpl.java b/java/com/google/gerrit/sshd/SshKeyCreatorImpl.java
index d89f9e0c2e..e2fbdcb2af 100644
--- a/java/com/google/gerrit/sshd/SshKeyCreatorImpl.java
+++ b/java/com/google/gerrit/sshd/SshKeyCreatorImpl.java
@@ -34,11 +34,10 @@ public class SshKeyCreatorImpl implements SshKeyCreator {
       SshUtil.parse(key);
       return key;
     } catch (NoSuchAlgorithmException | InvalidKeySpecException e) {
-      throw new InvalidSshKeyException();
-
+      throw new InvalidSshKeyException(e);
     } catch (NoSuchProviderException e) {
       logger.atSevere().withCause(e).log("Cannot parse SSH key");
-      throw new InvalidSshKeyException();
+      throw new InvalidSshKeyException(e);
     }
   }
 }
diff --git a/java/com/google/gerrit/sshd/SuExec.java b/java/com/google/gerrit/sshd/SuExec.java
index 7053a0d5f4..6d0bf2bc3f 100644
--- a/java/com/google/gerrit/sshd/SuExec.java
+++ b/java/com/google/gerrit/sshd/SuExec.java
@@ -126,9 +126,9 @@ public final class SuExec extends BaseCommand {
       try {
         permissionBackend.user(caller).check(GlobalPermission.RUN_AS);
       } catch (AuthException e) {
-        throw die("suexec not permitted");
+        throw die("suexec not permitted", e);
       } catch (PermissionBackendException e) {
-        throw die("suexec not available: " + e);
+        throw die("suexec not available", e);
       }
     }
   }
diff --git a/java/com/google/gerrit/sshd/commands/LsUserRefs.java b/java/com/google/gerrit/sshd/commands/LsUserRefs.java
index 856c8a5545..f68e34c9de 100644
--- a/java/com/google/gerrit/sshd/commands/LsUserRefs.java
+++ b/java/com/google/gerrit/sshd/commands/LsUserRefs.java
@@ -105,9 +105,9 @@ public class LsUserRefs extends SshCommand {
         throw new Failure(1, "fatal: Error reading refs: '" + projectName, e);
       }
     } catch (RepositoryNotFoundException e) {
-      throw die("'" + projectName + "': not a git archive");
+      throw die("'" + projectName + "': not a git archive", e);
     } catch (IOException | OrmException e) {
-      throw die("Error opening: '" + projectName);
+      throw die("Error opening: '" + projectName, e);
     }
   }
 }
diff --git a/java/com/google/gerrit/sshd/commands/PatchSetParser.java b/java/com/google/gerrit/sshd/commands/PatchSetParser.java
index 8dee69ee02..2dd035c937 100644
--- a/java/com/google/gerrit/sshd/commands/PatchSetParser.java
+++ b/java/com/google/gerrit/sshd/commands/PatchSetParser.java
@@ -104,7 +104,7 @@ public class PatchSetParser {
       try {
         patchSetId = PatchSet.Id.parse(token);
       } catch (IllegalArgumentException e) {
-        throw error("\"" + token + "\" is not a valid patch set");
+        throw error("\"" + token + "\" is not a valid patch set", e);
       }
       ChangeNotes notes = getNotes(projectState, patchSetId.getParentKey());
       PatchSet patchSet = psUtil.get(db.get(), notes, patchSetId);
@@ -135,7 +135,7 @@ public class PatchSetParser {
       ChangeNotes notes = changeFinder.findOne(changeId);
       return notesFactory.create(db.get(), notes.getProjectName(), changeId);
     } catch (NoSuchChangeException e) {
-      throw error("\"" + changeId + "\" no such change");
+      throw error("\"" + changeId + "\" no such change", e);
     }
   }
 
@@ -158,4 +158,8 @@ public class PatchSetParser {
   public static UnloggedFailure error(String msg) {
     return new UnloggedFailure(1, msg);
   }
+
+  public static UnloggedFailure error(String msg, Throwable why) {
+    return new UnloggedFailure(1, msg, why);
+  }
 }
diff --git a/java/com/google/gerrit/sshd/commands/PluginInstallCommand.java b/java/com/google/gerrit/sshd/commands/PluginInstallCommand.java
index 8b045ec838..cfb47f7d0c 100644
--- a/java/com/google/gerrit/sshd/commands/PluginInstallCommand.java
+++ b/java/com/google/gerrit/sshd/commands/PluginInstallCommand.java
@@ -70,21 +70,21 @@ final class PluginInstallCommand extends PluginAdminSshCommand {
       try {
         data = Files.newInputStream(new File(source).toPath());
       } catch (IOException e) {
-        throw die("cannot read " + source);
+        throw die("cannot read " + source, e);
       }
     } else {
       try {
         data = new URL(source).openStream();
       } catch (MalformedURLException e) {
-        throw die("invalid url " + source);
+        throw die("invalid url " + source, e);
       } catch (IOException e) {
-        throw die("cannot read " + source);
+        throw die("cannot read " + source, e);
       }
     }
     try {
       loader.installPluginFromStream(name, data);
     } catch (IOException e) {
-      throw die("cannot install plugin");
+      throw die("cannot install plugin", e);
     } catch (PluginInstallException e) {
       e.printStackTrace(stderr);
       String msg = String.format("Plugin failed to install. Cause: %s", e.getMessage());
diff --git a/java/com/google/gerrit/sshd/commands/Receive.java b/java/com/google/gerrit/sshd/commands/Receive.java
index fa0e37b247..53a9ca252b 100644
--- a/java/com/google/gerrit/sshd/commands/Receive.java
+++ b/java/com/google/gerrit/sshd/commands/Receive.java
@@ -83,7 +83,7 @@ final class Receive extends AbstractGitCommand {
           .project(project.getNameKey())
           .check(ProjectPermission.RUN_RECEIVE_PACK);
     } catch (AuthException e) {
-      throw new Failure(1, "fatal: receive-pack not permitted on this server");
+      throw new Failure(1, "fatal: receive-pack not permitted on this server", e);
     } catch (PermissionBackendException e) {
       throw new Failure(1, "fatal: unable to check permissions " + e);
     }
diff --git a/java/com/google/gerrit/sshd/commands/ReviewCommand.java b/java/com/google/gerrit/sshd/commands/ReviewCommand.java
index bc8ef2af28..786048fc03 100644
--- a/java/com/google/gerrit/sshd/commands/ReviewCommand.java
+++ b/java/com/google/gerrit/sshd/commands/ReviewCommand.java
@@ -322,7 +322,7 @@ public class ReviewCommand extends SshCommand {
     try {
       allProjectsState = projectCache.checkedGet(allProjects);
     } catch (IOException e) {
-      throw die("missing " + allProjects.get());
+      throw die("missing " + allProjects.get(), e);
     }
 
     for (LabelType type : allProjectsState.getLabelTypes().getLabelTypes()) {
diff --git a/java/com/google/gerrit/sshd/commands/Upload.java b/java/com/google/gerrit/sshd/commands/Upload.java
index 24a6975867..6b5dd7533d 100644
--- a/java/com/google/gerrit/sshd/commands/Upload.java
+++ b/java/com/google/gerrit/sshd/commands/Upload.java
@@ -55,9 +55,9 @@ final class Upload extends AbstractGitCommand {
 
       perm.check(ProjectPermission.RUN_UPLOAD_PACK);
     } catch (AuthException e) {
-      throw new Failure(1, "fatal: upload-pack not permitted on this server");
+      throw new Failure(1, "fatal: upload-pack not permitted on this server", e);
     } catch (PermissionBackendException e) {
-      throw new Failure(1, "fatal: unable to check permissions " + e);
+      throw new Failure(1, "fatal: unable to check permissions ", e);
     }
 
     final UploadPack up = new UploadPack(repo);
diff --git a/tools/BUILD b/tools/BUILD
index 961af1e163..b66a1a88b1 100644
--- a/tools/BUILD
+++ b/tools/BUILD
@@ -83,6 +83,7 @@ java_package_configuration(
         "-Xep:TypeParameterUnusedInFormals:WARN",
         "-Xep:URLEqualsHashCode:WARN",
         "-Xep:UnsynchronizedOverridesSynchronized:WARN",
+        "-Xep:UnusedException:ERROR",
         "-Xep:WaitNotInLoop:WARN",
     ],
     packages = ["error_prone_packages"],