fix

common/modules/sessions/views/statistics-admin/details.php

@@ -17,9 +17,9 @@ $this->params['breadcrumbs'][] = $this->title;
         'filterModel' => $searchModel,
         'columns' => [
             // ['class' => 'yii\grid\SerialColumn'],
-            
+
             [
-                'attributes' => 'created_at',
+                'attribute' => 'created_at',
                 'value' => function($model) {
                     return date('d.m.Y H:i:s', $model->created_at);
                 }

common/modules/sessions/views/statistics-admin/manage.php

@@ -20,7 +20,7 @@ $this->params['breadcrumbs'][] = $this->title;
             // ['class' => 'yii\grid\SerialColumn'],
             
             [
-                'attributes' => 'created_at',
+                'attribute' => 'created_at',
                 'value' => function($model) {
                     return date('d.m.Y H:i:s', $model->created_at);
                 }