Are you using a password add-on or program?

Start Firefox using Troubleshoot(Safe) Mode {web link}

A small dialog should appear. Click Start In Troubleshoot(Safe) Mode (not Refresh). Is the problem still there?

That didn't work. Any other ideas? Thanks

Did anything happen to your profile? Any kind of data coruption?

What about the rest of your profile? Settings, bookmarks, history, passwords . . . .

Use these links to create a new profile. Use this new profile as is. Is the problem still there?

https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

http://kb.mozillazine.org/Profile_folder_-_Firefox#Navigating_to_the_profile_folder

https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

Type about:profiles<enter> in the address bar. How many profiles are listed? How many should be there? Also, open the profile folder in your file explorer.

https://support.mozilla.org/en-US/kb/recover-user-data-missing-after-firefox-update

I assume something was corrupted when FF automatically updated, but there is no way to tell. Everything else works. I have my bookmarks. There is no other profile. I tried using troubleshooting mode, but it didn't work.