diff --git a/lib/classes/UserManagement.class.php b/lib/classes/UserManagement.class.php
index 7dd38eaa570d5020e530f86e4086d190b44b43a1..3efae35004725f7f08ddb40109f51b2c364585d6 100644
--- a/lib/classes/UserManagement.class.php
+++ b/lib/classes/UserManagement.class.php
@@ -585,10 +585,6 @@ class UserManagement
             if ($count = UserStudyCourse::deleteBySQL('user_id = ?', [$this->user_data['auth_user_md5.user_id']])) {
                 $this->msg .= 'info§' . sprintf(_('%s Zuordnungen zu Studiengängen gelöscht.'), $count) . '§';
             }
-            // delete all private appointments of this user
-            if ($count = delete_range_of_dates($this->user_data['auth_user_md5.user_id'], false)) {
-                $this->msg .= 'info§' . sprintf(_('%s Einträge aus den Terminen gelöscht.'), $count) . '§';
-            }
         }
 
         if ($newuser['auth_user_md5.perms'] === 'admin') {
diff --git a/lib/classes/auth_plugins/StudipAuthAbstract.class.php b/lib/classes/auth_plugins/StudipAuthAbstract.class.php
index fd2d4e9aaff48eede1462ce8cb815e2330c305dd..36c75df646faa36d368dbfd94c1e1f4dbec64c77 100644
--- a/lib/classes/auth_plugins/StudipAuthAbstract.class.php
+++ b/lib/classes/auth_plugins/StudipAuthAbstract.class.php
@@ -125,7 +125,7 @@ class StudipAuthAbstract
                 self::$plugin_instances[strtoupper($plugin)] = new $plugin_class($config);
             }
         }
-        return ($plugin_name) ? self::$plugin_instances[strtoupper($plugin_name)] : self::$plugin_instances;
+        return ($plugin_name) ? self::$plugin_instances[strtoupper($plugin_name)]??null : self::$plugin_instances;
     }
 
     /**