since 2.0.13, the class name Object is invalid since PHP 7.2, use [[BaseObject]] instead. (yiisoft#151)

Author: schmasterz

models/User.php

@@ -2,7 +2,7 @@
 
 namespace app\models;
 
-class User extends \yii\base\Object implements \yii\web\IdentityInterface
+class User extends \yii\base\BaseObject implements \yii\web\IdentityInterface
 {
     public $id;
     public $username;