diff --git a/src/main/resources/web/js/rs/collections/aggregates.js b/src/main/resources/web/js/rs/collections/aggregates.js
index bbf5a45..bffb7da 100644
--- a/src/main/resources/web/js/rs/collections/aggregates.js
+++ b/src/main/resources/web/js/rs/collections/aggregates.js
@@ -127,7 +127,9 @@ define([
         success(err, onionooVersion, buildRevision, relaysPublished,
                 bridgesPublished);
       }).fail(function(jqXHR, textStatus, errorThrown) {
-        if(jqXHR.statusText == "error") {
+        if (jqXHR.status / 100 == 4) {
+          error(4);
+        } else if (jqXHR.statusText == "error") {
           error(2);
         } else {
           error(3);
diff --git a/src/main/resources/web/js/rs/collections/results.js b/src/main/resources/web/js/rs/collections/results.js
index 0110b7b..dfec6df 100644
--- a/src/main/resources/web/js/rs/collections/results.js
+++ b/src/main/resources/web/js/rs/collections/results.js
@@ -78,7 +78,9 @@ define([
                 chunkedLookup();
             }).fail(
                 function(jqXHR, textStatus, errorThrown) {
-                if(jqXHR.statusText == "error") {
+                if (jqXHR.status / 100 == 4) {
+                    error(4);
+                } else if(jqXHR.statusText == "error") {
                     error(2);
                 } else {
                     error(3);
diff --git a/src/main/resources/web/templates/rs/aggregate/map.html b/src/main/resources/web/templates/rs/aggregate/map.html
index b30e800..8ecb359 100644
--- a/src/main/resources/web/templates/rs/aggregate/map.html
+++ b/src/main/resources/web/templates/rs/aggregate/map.html
@@ -25,6 +25,13 @@
 	backend IP address. If the problem persits consult <a
 		href="https://trac.torproject.org/">the bugtracker.</a></p>
     </div>
+    <% } else if (error == 4) { %>
+    <div class="alert alert-danger">
+        <strong>Query error!</strong><p>The backend server reports a problem
+        with your query. Please have a look at
+        <a href="#about">the About page</a> that explains what type of search
+        queries are supported by Relay Search.</p>
+    </div>
     <% } else if (error == 5) { %>
     <div class="alert alert-warning">
         <strong>No query submitted!</strong>
diff --git a/src/main/resources/web/templates/rs/aggregate/search.html b/src/main/resources/web/templates/rs/aggregate/search.html
index 151afb6..3046160 100644
--- a/src/main/resources/web/templates/rs/aggregate/search.html
+++ b/src/main/resources/web/templates/rs/aggregate/search.html
@@ -26,6 +26,13 @@
 	backend IP address. If the problem persits consult <a
 		href="https://trac.torproject.org/">the bugtracker.</a></p>
     </div>
+    <% } else if (error == 4) { %>
+    <div class="alert alert-danger">
+        <strong>Query error!</strong><p>The backend server reports a problem
+        with your query. Please have a look at
+        <a href="#about">the About page</a> that explains what type of search
+        queries are supported by Relay Search.</p>
+    </div>
     <% } else if (error == 5) { %>
     <div class="alert alert-warning">
         <strong>No query submitted!</strong>
diff --git a/src/main/resources/web/templates/rs/search/do.html b/src/main/resources/web/templates/rs/search/do.html
index 1fe06b4..e2a669d 100644
--- a/src/main/resources/web/templates/rs/search/do.html
+++ b/src/main/resources/web/templates/rs/search/do.html
@@ -26,6 +26,13 @@
 	backend IP address. If the problem persits consult <a
 		href="https://trac.torproject.org/">the bugtracker.</a></p>
     </div>
+    <% } else if (error == 4) { %>
+    <div class="alert alert-danger">
+	<strong>Query error!</strong><p>The backend server reports a problem
+        with your query. Please have a look at
+	<a href="#about">the About page</a> that explains what type of search
+        queries are supported by Relay Search.</p>
+    </div>
     <% } else if (error == 5) { %>
     <div class="alert alert-warning">
         <strong>No query submitted!</strong>