Notice (1024) : Undefined property: UsersController::$Authentication in /homepages/19/d682435178/htdocs/33planning/src/Controller/UsersController.php on line 23 [in /homepages/19/d682435178/htdocs/33planning/vendor/cakephp/cakephp/src/Controller/Controller.php, line 342]
Warning (512) : Unable to emit headers. Headers sent in file=/homepages/19/d682435178/htdocs/33planning/vendor/cakephp/cakephp/src/Error/Renderer/HtmlErrorRenderer.php line=37 [in /homepages/19/d682435178/htdocs/33planning/vendor/cakephp/cakephp/src/Http/ResponseEmitter.php, line 71]
Warning (2) : Cannot modify header information - headers already sent by (output started at /homepages/19/d682435178/htdocs/33planning/vendor/cakephp/cakephp/src/Error/Renderer/HtmlErrorRenderer.php:37) [in /homepages/19/d682435178/htdocs/33planning/vendor/cakephp/cakephp/src/Http/ResponseEmitter.php, line 164]
Warning (2) : Cannot modify header information - headers already sent by (output started at /homepages/19/d682435178/htdocs/33planning/vendor/cakephp/cakephp/src/Error/Renderer/HtmlErrorRenderer.php:37) [in /homepages/19/d682435178/htdocs/33planning/vendor/cakephp/cakephp/src/Http/ResponseEmitter.php, line 197]
Error: Call to a member function addUnauthenticatedActions() on null

Call to a member function addUnauthenticatedActions() on null 📋

Error
Error in: APP/Controller/UsersController.php, line 23
APP/Controller/UsersController.php at line 23 (edit)
    public function beforeFilter(EventInterface $event)
    {
        parent::beforeFilter($event);
        $this->Authentication->addUnauthenticatedActions([
            'login', 'logout', 'forgot', 'password', 'activate',
        ]);
        $this->FormProtection->setConfig('unlockedActions', ['login']);
    }

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