TYPO3 Core

HOW TO REPRODUCE:
1. Setup ext:news
2. Setup routing configuration for ext:news
3. Setup frontend user login and log to website
4. Set some news to be avaliable only for logged users (fe_groups)
5. The news will be visible on list view but when you click single news link you will see 404 error

THE REASON:
The reason is that router matcher can not read record because wrong frontend group are returned by GeneralUtility::makeInstance(Context::class)->getAspect('frontend.user') because user->groupData is not yet filled at this time.

MORE INFO:
In file typo3/sysext/frontend/Classes/Middleware/PageResolver.php at line 111 there is check for:

$pageArguments = $site->getRouter()->matchRequest($request, $previousResult);

Inside this check there is query that use TYPO3\CMS\Core\Database\Query\Restriction\FrontendGroupRestriction. In the constructor of the FrontendGroupRestriction there is

$frontendUserAspect = GeneralUtility::makeInstance(Context::class)->getAspect('frontend.user');

This $frontendUserAspect has method getGroupIds() which use isLoggedIn() which checks for $this->user->groupData['uid'] but on this level there is no yet $this->user->groupData because it will be generated in file typo3/sysext/frontend/Classes/Middleware/PageResolver.php at line 158 $this->controller->determineId()