Where does Firefox save a file listing current open tabs/windows (Manjaro Linux)? [View all]

I tried to do an upgrade on an old version of Manjaro and ran into the usual conflicts, broken dependencies, and corrupt PGP signatures. Tried to reinstall Firefox and only got an error message that installation failed -- but Firefox app was gone. There is still a Firefox folder in my home directory, and I've archived that. Can't install Firefox because of the same corrupt PGP error.

I think I will have to reinstall Manjaro but don't want to lose open tabs (I always reopen with dozens of tabs from previous sessions). Any way to do that ? Note that I'm talking about tabs, not bookmarks, though I'd like to recover those too (and even History if that's possible.) Suggestions appreciated -- thanks in advance !