diff --git a/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header.js b/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header.js
index 1dcedd1e5b..ccf0f5705a 100644
--- a/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header.js
+++ b/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header.js
@@ -111,11 +111,10 @@
       },
       _docBaseUrl: {
         type: String,
-        value: null,
       },
       _links: {
         type: Array,
-        computed: '_computeLinks(_defaultLinks, _userLinks, _adminLinks,' +
+        computed: '_computeLinks(_defaultLinks, _userLinks, _adminLinks, ' +
             '_docBaseUrl)',
       },
       _loginURL: {
@@ -220,10 +219,23 @@
     },
 
     _loadConfig: function() {
-      return this.$.restAPI.getConfig().then(function(config) {
+      this.$.restAPI.getConfig().then(function(config) {
         if (config && config.gerrit) {
           this._docBaseUrl = config.gerrit.doc_url;
         }
+        if (!this._docBaseUrl) {
+          return this._probeDocLink('/Documentation/index.html');
+        }
+      }.bind(this));
+    },
+
+    _probeDocLink: function(path) {
+      return this.$.restAPI.probePath(path).then(function(ok) {
+        if (ok) {
+          this._docBaseUrl = '/Documentation';
+        } else {
+          this._docBaseUrl = null;
+        }
       }.bind(this));
     },
 
diff --git a/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header_test.html b/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header_test.html
index abb1f546c1..4582b4f9c2 100644
--- a/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header_test.html
+++ b/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header_test.html
@@ -41,6 +41,7 @@ limitations under the License.
       sandbox = sinon.sandbox.create();
       stub('gr-rest-api-interface', {
         getConfig: function() { return Promise.resolve({}); },
+        probePath: function(path) { return Promise.resolve(false); },
       });
       stub('gr-main-header', {
         _loadAccount: function() {},
@@ -135,7 +136,7 @@ limitations under the License.
       var docLinks = [
         {
           name: 'Table of Contents',
-          url: '/Documentation/index.html',
+          url: '/index.html',
         },
       ];
 
@@ -147,13 +148,13 @@ limitations under the License.
       assert.deepEqual(element._getDocLinks('base', docLinks), [{
         name: 'Table of Contents',
         target: '_blank',
-        url: 'base/Documentation/index.html',
+        url: 'base/index.html',
       }]);
 
       assert.deepEqual(element._getDocLinks('base/', docLinks), [{
         name: 'Table of Contents',
         target: '_blank',
-        url: 'base/Documentation/index.html',
+        url: 'base/index.html',
       }]);
     });
   });
diff --git a/polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.js b/polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.js
index 8ae56ef70e..66a69a1a46 100644
--- a/polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.js
+++ b/polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.js
@@ -1052,5 +1052,12 @@
       return this.send('DELETE',
           this.getChangeActionURL(changeNum, null, '/assignee'));
     },
+
+    probePath: function(path) {
+      return fetch(new Request(path, {method: 'HEAD'}))
+        .then(function(response) {
+          return response.ok;
+        });
+    },
   });
 })();