diff --git a/repository/repository_ajax.php b/repository/repository_ajax.php
index f679c785b95f7..d2b1dec2c4a4f 100644
--- a/repository/repository_ajax.php
+++ b/repository/repository_ajax.php
@@ -57,7 +57,6 @@
 $PAGE->set_context($context);
 
 echo $OUTPUT->header(); // send headers
-@header('Content-type: text/html; charset=utf-8');
 
 // If uploaded file is larger than post_max_size (php.ini) setting, $_POST content will be empty.
 if (empty($_POST) && !empty($action)) {
diff --git a/user/selector/lib.php b/user/selector/lib.php
index 00bcd7e9d229b..18e9dfc5b353b 100644
--- a/user/selector/lib.php
+++ b/user/selector/lib.php
@@ -70,7 +70,7 @@ abstract class user_selector_base {
     protected static $jsmodule = array(
                 'name' => 'user_selector',
                 'fullpath' => '/user/selector/module.js',
-                'requires'  => array('node', 'event-custom', 'datasource', 'json'),
+                'requires'  => array('node', 'event-custom', 'datasource', 'json', 'moodle-core-notification'),
                 'strings' => array(
                     array('previouslyselectedusers', 'moodle', '%%SEARCHTERM%%'),
                     array('nomatchingusers', 'moodle', '%%SEARCHTERM%%'),
diff --git a/user/selector/module.js b/user/selector/module.js
index 24daf821b4911..ca89434172b07 100644
--- a/user/selector/module.js
+++ b/user/selector/module.js
@@ -151,8 +151,7 @@ M.core_user.init_user_selector = function (Y, name, hash, extrafields, lastsearc
                 method: 'POST',
                 data: 'selectorid='+hash+'&sesskey='+M.cfg.sesskey+'&search='+value + '&userselector_searchanywhere=' + this.get_option('searchanywhere'),
                 on: {
-                    success:this.handle_response,
-                    failure:this.handle_failure
+                    complete: this.handle_response
                 },
                 context:this
             });
@@ -175,26 +174,15 @@ M.core_user.init_user_selector = function (Y, name, hash, extrafields, lastsearc
                 }
                 this.listbox.setStyle('background','');
                 var data = Y.JSON.parse(response.responseText);
+                if (data.error) {
+                    this.searchfield.addClass('error');
+                    return new M.core.ajaxException(data);
+                }
                 this.output_options(data);
             } catch (e) {
-                this.handle_failure(requestid);
-            }
-        },
-        /**
-         * Handles what happens when the ajax request fails.
-         */
-        handle_failure : function(requestid) {
-            delete this.iotransactions[requestid];
-            if (!Y.Object.isEmpty(this.iotransactions)) {
-                // More searches pending. Wait until they are all done.
-                return;
-            }
-            this.listbox.setStyle('background','');
-            this.searchfield.addClass('error');
-
-            // If we are in developer debug mode, output a link to help debug the failure.
-            if (M.cfg.developerdebug) {
-                this.searchfield.insert(Y.Node.create('<a href="'+M.cfg.wwwroot +'/user/selector/search.php?selectorid='+hash+'&sesskey='+M.cfg.sesskey+'&search='+this.get_search_text()+'&debug=1">Ajax call failed. Click here to try the search call directly.</a>'));
+                this.listbox.setStyle('background','');
+                this.searchfield.addClass('error');
+                return new M.core.exception(e);
             }
         },
         /**
@@ -379,4 +367,4 @@ M.core_user.init_user_selector_options_tracker = function(Y) {
     user_selector_options_tracker.init();
     // Return it just incase it is ever wanted
     return user_selector_options_tracker;
-};
\ No newline at end of file
+};
diff --git a/user/selector/search.php b/user/selector/search.php
index a7b8d9cb9ecec..22826a6eff83f 100644
--- a/user/selector/search.php
+++ b/user/selector/search.php
@@ -23,29 +23,19 @@
  * @package user
  */
 
+define('AJAX_SCRIPT', true);
+
 require_once(dirname(__FILE__) . '/../../config.php');
 require_once($CFG->dirroot . '/user/selector/lib.php');
 
 $PAGE->set_context(context_system::instance());
 $PAGE->set_url('/user/selector/search.php');
 
-// In developer debug mode, when there is a debug=1 in the URL send as plain text
-// for easier debugging.
-if (debugging('', DEBUG_DEVELOPER) && optional_param('debug', false, PARAM_BOOL)) {
-    header('Content-type: text/plain; charset=UTF-8');
-    $debugmode = true;
-} else {
-    header('Content-type: application/json; charset=utf-8');
-    $debugmode = false;
-}
+echo $OUTPUT->header();
 
 // Check access.
-if (!isloggedin()) {;
-    print_error('mustbeloggedin');
-}
-if (!confirm_sesskey()) {
-    print_error('invalidsesskey');
-}
+require_login();
+require_sesskey();
 
 // Get the search parameter.
 $search = required_param('search', PARAM_RAW);
@@ -59,13 +49,6 @@
 // Get the options.
 $options = $USER->userselectors[$selectorhash];
 
-if ($debugmode) {
-    echo 'Search string: ', $search, "\n";
-    echo 'Options: ';
-    print_r($options);
-    echo "\n";
-}
-
 // Create the appropriate userselector.
 $classname = $options['class'];
 unset($options['class']);