Today I noticed that I could not open Lightroom Classic 10.1 anymore on my Macbook Pro with Mac OS Big Sure (version 11.1). It does not crash (no messages are being shown). If I click the app icon I briefly see the start-up screen after which it closes. There doesn't seem to be a locked .lrcat file. If I try to open LRC via the .lrcat file It shows a message that LRC has crashed.
I also have already uninstalled and reinstalled LRC and restarted my MacBook.
Try going back to LrC 10.0
Thanks. I just installed version 10.0 but with the exact same result.... (I uninstalled 10.1 including all preferences).
Lots of problem LrC 10 and macOS Big Sur see the feedback forum.
Thanks, again without any results. It still only briefly shows the start screen. That's it.
Try starting Lightroom without a catalog, so that it should ask you for it and give you a chance to create a new one. Move your catalog folder from its current location to another location, and then start Lightroom. If Lightroom does start and asks you to locate the catalog, then create a new one and see if that works. If that works, you can try to import the old one (Import from Another Catalog) to create a new working catalog with all your images and edits intact.
I tried, but every time it's the same result... it starts, you see the initial loading screen and that's it. No error, no questions regarding catalogs, no nothing.
Also tried version 9.4, same again. Seems Lightroom doesn't work well with macOS Big Sure at the moment.
Big Sur might be a coincidence. I have two computers running Big Sur and Lightroom very happily. Ask help here: https://feedback.photoshop.com (search the forum first for people who have the same problem. If you find a thread, then add your experience there and do not create a new thread). That is the feedback forum for bugs and requests. This is a user-to-user forum, so we have limited possibilities to solve this.