Notice (1024) : Undefined property `ErrorController::$Authentication` in `/mnt/web124/e2/77/5404677/htdocs/quartier-portal/src/Controller/AppController.php` on line 70 [in /mnt/web124/e2/77/5404677/htdocs/quartier-portal/vendor/cakephp/cakephp/src/Controller/Controller.php, line 316]
Warning (512) : Unable to emit headers. Headers sent in file=/mnt/web124/e2/77/5404677/htdocs/quartier-portal/vendor/cakephp/cakephp/src/Error/Renderer/HtmlErrorRenderer.php line=37 [in /mnt/web124/e2/77/5404677/htdocs/quartier-portal/vendor/cakephp/cakephp/src/Http/ResponseEmitter.php, line 65]
Warning (2) : Cannot modify header information - headers already sent by (output started at /mnt/web124/e2/77/5404677/htdocs/quartier-portal/vendor/cakephp/cakephp/src/Error/Renderer/HtmlErrorRenderer.php:37) [in /mnt/web124/e2/77/5404677/htdocs/quartier-portal/vendor/cakephp/cakephp/src/Http/ResponseEmitter.php, line 159]
Warning (2) : Cannot modify header information - headers already sent by (output started at /mnt/web124/e2/77/5404677/htdocs/quartier-portal/vendor/cakephp/cakephp/src/Error/Renderer/HtmlErrorRenderer.php:37) [in /mnt/web124/e2/77/5404677/htdocs/quartier-portal/vendor/cakephp/cakephp/src/Http/ResponseEmitter.php, line 192]
Error: Controller class `Zurück` could not be found.

Controller class `Zurück` could not be found. 📋

Cake\Http\Exception\MissingControllerException
CORE/src/Controller/ControllerFactory.php at line 335 (edit)
     * @return \Cake\Http\Exception\MissingControllerException
     */
    protected function missingController(ServerRequest $request): MissingControllerException
    {
        return new MissingControllerException([
            'controller' => $request->getParam('controller'),
            'plugin' => $request->getParam('plugin'),
            'prefix' => $request->getParam('prefix'),
            '_ext' => $request->getParam('_ext'),

If you want to customize this error message, create templates/Error/error500.php