diff --git a/java/com/google/gerrit/extensions/restapi/UnprocessableEntityException.java b/java/com/google/gerrit/extensions/restapi/UnprocessableEntityException.java
index 9ed83b2d17..c1a9ad2be0 100644
--- a/java/com/google/gerrit/extensions/restapi/UnprocessableEntityException.java
+++ b/java/com/google/gerrit/extensions/restapi/UnprocessableEntityException.java
@@ -21,4 +21,8 @@ public class UnprocessableEntityException extends RestApiException {
   public UnprocessableEntityException(String msg) {
     super(msg);
   }
+
+  public UnprocessableEntityException(String msg, Throwable cause) {
+    super(msg, cause);
+  }
 }
diff --git a/java/com/google/gerrit/server/restapi/change/Rebase.java b/java/com/google/gerrit/server/restapi/change/Rebase.java
index dbb792a155..3165436480 100644
--- a/java/com/google/gerrit/server/restapi/change/Rebase.java
+++ b/java/com/google/gerrit/server/restapi/change/Rebase.java
@@ -168,7 +168,7 @@ public class Rebase extends RetryingRestModifyView<RevisionResource, RebaseInput
       }
     } catch (NoSuchChangeException e) {
       throw new UnprocessableEntityException(
-          String.format("Base change not found: %s", input.base));
+          String.format("Base change not found: %s", input.base), e);
     }
 
     PatchSet.Id baseId = base.patchSet().getId();