Fatal error: Uncaught Error: Class "yii\helpers\Json" not found in /home/telefonai/public_html/test.telefonai.eu/vendor/craftcms/cms/src/helpers/Json.php:19 Stack trace: #0 {main} thrown in /home/telefonai/public_html/test.telefonai.eu/vendor/craftcms/cms/src/helpers/Json.php on line 19