I am on Windows 10 Pro (extended to Oct 2026) and use the Firefox profile manager at startup since I have more than one profile. Today (11/12/2025) I attempted to start Firefox and the profile manager window would not populate. the window was blindingly white on my dark background. I closed and restarted umpteen times but it refused relentlessly. I was about to uninstall firefox and then decided to see if I had actually installed it on any of my mobile devices. And indeed I had it on my ancient Apple iPhone 7+. And it was synced! I refreshed the sync and indeed it picked up my most recent activity from last night. All tabs were synced. To make sure I had another synced copy I also installed it on my iPad. I synchronized this too and suddenly my desktop browser started working again.

I don't know what caused the lockup of the Profile Manager but I am afraid it might happen again. What causes this and what can I do to regain control without having to reinstall? I am a researcher and I have over 1000 tabs open.