Indexing of pages failes: Could not create a valid URL to get frontend data ...

[intertain]

Hi, I have a problem indexing pages in Backend. Indexing of news is working.

TYPO3 11.5.12 PHP 8.1 (too high? It worked with PHP 8.0 on DEV Server )

1311080805: RuntimeException: Could not create a valid URL to get frontend data while trying to index a page. Created URL: (...)/kontakt-formular in /var/www/(...)/typo3conf/ext/solr/Classes/Domain/Index/PageIndexer/Helper/UriBuilder/AbstractUriStrategy.php:111 Stack trace: #0 /var/www/rw_bodensee_p/releases/0/public/typo3conf/ext/solr/Classes/IndexQueue/PageIndexer.php(253): ApacheSolrForTypo3\Solr\Domain\Index\PageIndexer\Helper\UriBuilder\AbstractUriStrategy->getPageIndexingUriFromPageItemAndLanguageId()

Any idea?