diff --git a/application/controllers/ConfigController.php b/application/controllers/ConfigController.php
index 2205bc4b2..6358bb42d 100644
--- a/application/controllers/ConfigController.php
+++ b/application/controllers/ConfigController.php
@@ -3,7 +3,6 @@
 // {{{ICINGA_LICENSE_HEADER}}}
 
 use Icinga\Web\Controller\BaseConfigController;
-use Icinga\Web\Widget\Tab;
 use Icinga\Web\Widget\AlertMessageBox;
 use Icinga\Web\Notification;
 use Icinga\Application\Modules\Module;
@@ -12,7 +11,6 @@ use Icinga\Web\Form;
 use Icinga\Web\Widget;
 use Icinga\Application\Icinga;
 use Icinga\Application\Config as IcingaConfig;
-use Icinga\Data\ResourceFactory;
 use Icinga\Form\Config\GeneralForm;
 use Icinga\Form\Config\Authentication\LdapBackendForm;
 use Icinga\Form\Config\Authentication\DbBackendForm;
@@ -21,6 +19,7 @@ use Icinga\Form\Config\ResourceForm;
 use Icinga\Form\Config\LoggingForm;
 use Icinga\Form\Config\ConfirmRemovalForm;
 use Icinga\Config\PreservingIniWriter;
+use Icinga\Exception\ConfigurationError;
 
 
 /**
@@ -233,29 +232,34 @@ class ConfigController extends BaseConfigController
 
         $backendType = $this->getRequest()->getParam('type');
         $authenticationConfig = IcingaConfig::app('authentication')->toArray();
-        switch ($backendType) {
-            case 'ldap':
-                $form = new LdapBackendForm();
-                break;
-            case 'db':
-                $form = new DbBackendForm();
-                break;
-            case 'autologin':
-                $existing = array_filter($authenticationConfig, function ($e) { return $e['backend'] === 'autologin'; });
-                if (false === empty($existing)) {
-                    $this->addErrorMessage(
-                        $this->translate('An autologin backend already exists')
-                    );
+        try {
+            switch ($backendType) {
+                case 'ldap':
+                    $form = new LdapBackendForm();
+                    break;
+                case 'db':
+                    $form = new DbBackendForm();
+                    break;
+                case 'autologin':
+                    foreach ($authenticationConfig as $ac) {
+                        if (array_key_exists('backend', $ac) && $ac['backend'] === 'autologin') {
+                            throw new ConfigurationError(
+                                $this->translate('An autologin backend already exists')
+                            );
+                        }
+                    }
+                    $form = new AutologinBackendForm();
+                    break;
+                default:
+                    $this->addErrorMessage(sprintf(
+                        $this->translate('There is no backend type `%s\''),
+                        $backendType
+                    ));
                     $this->redirectNow('config/configurationerror');
-                }
-                $form = new AutologinBackendForm();
-                break;
-            default:
-                $this->addErrorMessage(sprintf(
-                    $this->translate('There is no backend type `%s\''),
-                    $backendType
-                ));
-                $this->redirectNow('config/configurationerror');
+            }
+        } catch (ConfigurationError $e) {
+            $this->addErrorMessage($e->getMessage());
+            $this->redirectNow('config/configurationerror');
         }
 
         $request = $this->getRequest();