Merge branch 'dev'

backend/controllers/UserController.php

@@ -158,7 +158,7 @@ class UserController extends BackendController
                 $userExist = false ;
                 $posts = Yii::$app->request->post() ;
 
-                if($posts) {
+                if($posts && isset($posts['User']['email']) && strlen($posts['User']['email']) > 0) {
                         $userExist = User::searchOne([
                                 'email' => $posts['User']['email']
                         ]);