Lightroom Classic lässt sich trotz Abo nicht öffnen

The first thing that you should try is to switch off the GPU support from the Lightroom preferences and check if that helps to fix the issue.

Go to Lightroom > Preferences > Performance tab > Uncheck "Use Graphics Processor" > Restart Lightroom.

https://helpx.adobe.com/lightroom-classic/kb/lightroom-gpu-faq.html#troubleshooting

https://helpx.adobe.com/lightroom-classic/kb/troubleshoot-gpu.html

If Lightroom doesn't start correctly the please see "Solution 2" in the document behind the second link.

Troubleshoot GPU issues | Lightroom Classic (adobe.com)

Another step is to try to reset the Lightroom preferences.

https://www.lightroomqueen.com/how-do-i-reset-lightrooms-preferences/

It's recommended to backup your preferences before you reset the preferences to the default settings:

https://helpx.adobe.com/lightroom-classic/kb/preference-file-and-other-file-locations.html

Did Lightroom Classic work previously?

If so, then the last time you used it, did you close it as normal, or did you force quit, or perhaps, did it crash?

If a force quit, or a crash, have you deleted the lock file that would still be in place (should have been deleted upon proper close)

Please Consider including the following in your question:

• Adobe product and version number
• Operating system and version number
• The full text of any error message (s)
• What you were doing when the problem occurred
• Screenshots of the problem
• Computer hardware, such as CPU; GPU; the amount of RAM; etc

Thanks. The above info will help to solve your problem.