I needed to update a client site to the latest version of Protected Pages due to the security release, but that caused this fatal error:
TypeError: Argument 1 passed to Drupal\protected_pages\EventSubscriber\ProtectedPagesSubscriber::checkProtectedPage() must be an instance of Symfony\Component\HttpKernel\Event\ResponseEvent, instance of Symfony\Component\HttpKernel\Event\FilterResponseEvent given in Drupal\protected_pages\EventSubscriber\ProtectedPagesSubscriber->checkProtectedPage() (line 107 of modules/contrib/protected_pages/src/EventSubscriber/ProtectedPagesSubscriber.php).
On a Drupal 8 site, upgrade to version 8.x-1.6, clear cache and try to load any page.
This seems to be caused by a commit that ran automated Drupal 10 compatibility fixes. So applying a patch that includes all but the problem commit seems to fix this (see attached patch).
Active
1.6
Code