I asked about this crash problem on 9/2/20, which was answered by FredMcD. Below is my response. I tried replying to FredMcD's email, not realizing it was "no-reply". Is there a better way to have some back-and-forth with you support folks than this awkward email method? Alan Feuerbacher On 9/1/2020 10:27 PM, Mozilla Support Forum wrote: > Mozilla Support > Firefox update crashed > FredMcD > Sep 1, 2020, 2:27:11 PM > > What about the rest of your profile? Settings, bookmarks, history, passwords . . . That stuff seems to be intact. > > You may have corrupt sessionstore [v56] sessionstore.jsonlz4 file(s). Delete all sessionstore* files and the sessionstore-backups folder. Where do I find those files/folders? > > Type about:support<enter> in the address bar. > > Under the page logo on the left side, you will see Application Basics. Under this find Profile Folder. To its right press the button Show Folder. This will open your file browser to the current Firefox profile. Now Close Firefox. Done. > > Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder I'm running Windows 10. > > Linux: Under the page logo on the left side, you will see Application Basics. Under this find Profile Directory. To its right press the button Open Directory. > > Locate the above file. Then rename or delete it. Restart Firefox. The above procedure found this folder: This PC > LocalDisk (C:) > Users > alanf > AppData > Roaming > Firefox > Profiles > dl1f50tv.default . I renamed the latter file to dl1f50tv_crashsave.default . I restarted the computer, then tried to restart Firefox. I got the message: "Profile Missing" "Your Firefox profile cannot be loaded. It may be missing or inaccessible." > > > Don't delete the files if you need to rescue any data from them, just move them out of the profile folder to some location where Firefox doesn't look for them. You can try to read out their contents using this tool: https://www.jeffersonscher.com/res/scrounger.html I did not try this, since I'm not really sure what file you meant by "Locate the above file." What next? Thanks for your help! Alan