Question website show not existing pages

[datenrettung]

Server operating system version

Ubuntu 16.04.7 LTS

Plesk version and microupdate number

Plesk Obsidian 18.0.34

Hello,My websites are displaying non-existent pages when incorrect URLs are entered. For example, accessing a valid URL works fine, but appending any extra path (e.g., "/a" or "/f") to it shows a not existing page instead of redirecting to the homepage.
Valid URL: https://hddlab.de/datenrettung/datenrettung-software.html
Invalid URL Example: https://hddlab.de/datenrettung/datenrettung-software.html

Current .htaccess rule:

RewriteEngine On
RewriteRule ^m/(.*)$ https://hddlab.de/$1 [R=301,L]

How can I modify my plesk configurations to redirect all non-existent pages back to the homepage? Thank you for your assistance.

 

[datenrettung]

Thanks, but after this modification the site show error on all pages: "
Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator to inform of the time the error occurred and of anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Web Server at hddlab.de
"