The two most common reasons would be: (1) You were using a newer version of Firefox before and you started up an older version. That doesn't look relevant since your Firefox reported itself to be the current version. (2) Your regular profile was marked as in use or locked, so Firefox created a new one to get you started. Please try the steps in the first section of the following article: [[Recover user data missing after Firefox update]] If Firefox isn't able to Launch the other profiles, you may need to do a regular shutdown/restart of Windows to release file locks.