TYPO3 Core

This might be a specific site config configuration issue, or from your base typoscript.

Can you try to setup up a minimal example to reproduce this with a site config plus base typoscript and put that here? Then we can try to help.

No problem, attached you'll find a zip-file containing a db dump and a home dir. You have to adjust the db-settings in file html/local/config/server-environment.php and the config/sites/site_theballandi/config.yaml and run composer install in the home dir, followed by ./local-deploy.sh, also from the home dir.

The site has no language menu, so you'll have to check the following url's directly in a browser:

en/mount/test - will give a 404
mount/test - is ok and gives 'Test'

Hi Garving, sorry for the delay, have been away. Here are a new zip of a site structure and sql dump. You can try whether the sql dump works with the site you already have, but probably better to start with the new structure, as it's a different site.

If you go to en/home, the second link to 'feedback', which is a mountpoint, will give a 'page not found'.
If you go to home, the second link to 'feedback' will give 'feedback'.

The problem seems to be which option you choose in the mountpoint settings of the page - see screenshot. If you choose 'Show the mounted page', the EN page gives a 404.