TYPO3 Core

My customer has a multi-side-domain-language installation, so he has multiple sites, multiple language and multiple domain in use.

Site config A:

• domain-A.com/en/, language 0
• domain-B.com/de/, language 1
  …
• domain-G.com/cns/, language 6

Site config B:

• domain-H.com/en/, language 0
• domain-I.com/cns/, language 6

In the page tree using site config B he uses mount points to pages of the tree using site config A. In versions before 11.5.18 it is working as expected, in version 11.5.18 it starts delivering a 404 for mount points which has a non translated slug in the none default value (translation overlay). Eg. domain-I.com/cns/page315/page430.html is a mount point to a page in the tree using site config A and the slug is not translated. In 11.5.17 and earlier it was working, for 11.5.18 and alter it shows a 404. If I translate the slug eg. domain-I.com/cns/page315-translated/page430-translated.html it starts working again.

I've checked the commits and saw a fix for #88715 and #96010 was applied with the commit:

2022-11-08 d2c466b04d [BUGFIX] Prevent resolving translated page with default slug (thanks to Stefan Bürk)

typo3/sysext/core/Classes/Routing/PageRouter.php#202

    if ($this->isRouteReallyValidForLanguage($matchedRoute, $language)) {
        return $this->buildPageArguments($matchedRoute, $result, $request->getQueryParams());
    }

The additional check isRouteReallyValidForLanguage causes the issue for me. After reverting back from 11.5.18 to 11.5.17 it works, upgrading again to 11.5.18 or later delivers 404 status in the FE.

Regards, Jens