My Lightroom has become unusuable because when I attempt to open it I get the message " The process cannot access the folder because it is being used by another process." I have run out of solutions. I am running Windows 11.
I assume that the same person posted this, which shows the exact same error message as in the Mac case, but he has a Windows computer
Later in that thread, he says Adobe tech support took over his computer and fixed the problem, but gave no hint (so far) as to what the solution was. Perhaps Adobe Tech support has logs of who called and what they did.
I used to get this with a cloud backup service. I had to exclude the folder the catalog lives to keep this from happening. With the catalog being constantly updated from Lightroom, my cloud backup was constantly trying to re-upload the file. I do make sure the catalog backups are set to upload.
I would make sure no other programs are accessing the file for any backup/catalog/indexing/mirroring processes. You could try running Windows in safe mode as a way to troubleshoot.