nach dem Start von LrC wird ein katalog gefunden, es werden aber keine Dateien angezeigt. Eine Bildschirmmeldung besagt: Die Datei wurde nicht gefunden. Auch die Wahl anderer Kataloge funktioniert nicht.

On which drive the catalog flies are located? If on a external drive, is the drive connected?

On a cloud drive (which isn’t recommended)? If yes, you are logged in and have access to the drive?

Do you have the appropriate access rights to the catalog folder?

What has been changed on your system before the error occur?

Please post a screenshot from the content of your recent catalog folder.

Do you’ve tried a cold boot of your computer?

Please provide a copy of your 'System Info'. This can be get from the Lightroom menu item Help > System Info. There's a copy button in the System Info dialog. Press this button and paste the info into your next forum post.

Try to hold the Ctrl-Key while starting LrC. This should opens a catalog selection dialog. Do this work and what is showing in this dialog?