I believe you can go to

Mac: ~/Library/Caches/Firefox/Profiles/ 

Close Firefox. Open your file browser to the above, and remove the folder.

to FULLY delete the cache, this thread might have more information too https://support.mozilla.org/en-US/questions/1269515

Thanks for your suggestion, Eve. Unfortunately, when I look at what's in Library/Caches/, there is no Firefox folder. The only folders there are (1) ColorSync, (2) com.apple.cloudkit, and (3) com.apple.iconservices.store.

Note that this is ~/Library/Caches/ in your home directory.

You can find a button on the about:profiles page to go to the secondary (local) profile location.

Note that this is ~/Library/Caches/ in your home directory.

I thought that is where I looked, unless my home directory has more than one Library.

I'm not sure which "about" you're referring to. Thanks, nonetheless.

I saved my bookmarks, deleted Firefox and all associated folders, rebooted, installed Firefox and the cache is now clear. That's the only fix I could find.

You can open "about:" pages via the location/address bar

• "about:" is a protocol to access special pages

See also:

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

Firefox uses two locations for the Firefox profile folder Location used for the main profile that keeps your personal data (Root Directory on about:profiles).

• ~/Library/Application Support/Firefox/Profiles/<profile>/

Location used for the disk cache and other temporary files (Local Directory on about:profiles).

• ~/Library/Caches/Firefox/Profiles/

Thanks, cor-el. I learned something new today.

Followed your instructions and was able to find where you meant. Sorry for the trouble, making you spell it all out for me.