Fatal error: Uncaught Error: Class "Atk4\Ui\JsCallback" not found in /home/.sites/site4/wwwroot/web/4.0/ui/src/UserAction/JsCallbackExecutor.php:29 Stack trace: #0 {main} thrown in /home/.sites/site4/wwwroot/web/4.0/ui/src/UserAction/JsCallbackExecutor.php on line 29