This is not a question about changing or preprocessing the twig template of the 403 page.

I have a controller with an access function called by the _custom_access key of my route.

In some circumstance, this function is returning AccessResult::forbidden("a good reason"); which lead to my default 403 page.

Most of the case, this is the behavior I would like to have, but in few cases, I would like to have another title and another message for this page like "You can not access because you eat too much chocolate"

Should I create a new custom error route and send a new response to this route from my access function? (hint: I tried without success)

Any idea?

Edit to add: Thanks to 4k4, I have added a custom ExceptionHtmlSubscriber extending DefaultExceptionHtmlSubscriber in order to override the on403() method.

Here is my code:

class TXSExceptionHtmlSubscriber extends DefaultExceptionHtmlSubscriber {   /**    * {@inheritdoc}    */   public function on403(ExceptionEvent $event) {     $my_condition=extract_from_event($event);     if($my_condition){       // I am not sure it is what should be done here       $this->makeSubrequest($event, '/my_custom_error_path/my_custom_error_code', Response::HTTP_FORBIDDEN);     }else {       parent::$this->on403($event);     }   }   /**    * {@inheritdoc}    */   protected static function getPriority() {     return 1000;   } } 

So far, I have 2 questions:

1-Unfortunately my custom on403() method is never called (on the other hand, the on403() method DefaultExceptionHtmlSubscriber is called): What I am missing?

2-Let say that my custom on403() method is called: what should be the code to redirect the user on my custom 403 page containing my custom message (ie: it could be nice to display the reason of the AccessResult AccessResult::forbidden("a good reason");