Where are the font caches located?

Start in safe boot mode, then restart as normal. It moves to the Trash all font cache.

All font caches normally stored in /Library/Caches/com.apple.ATS/(uid)/ , where (uid) is a user ID number such as 501 (Mac OS X v10.4 or later)

It moves to the Trash all font cache.

Not quite. It clears any and all cache files of the user account you logged into in Safe Mode. It doesn't do anything to the system cache files.

All font caches normally stored in /Library/Caches/com.apple.ATS/(uid)/ , where (uid) is a user ID number such as 501 (Mac OS X v10.4 or later)

I know that info came from one of Apple's own Knowledge Base articles, but it's completely out of date. The user font cache files haven't been in that location since Tiger. All font cache files (along with Font Book's database) are now deeply buried in a hidden folder. Part of the name may be different from Mac to Mac, but they are now here:

/private/var/folders/3K/3Kdt7kk4Ghim10j+GZwim++++TI/-Caches-/com.apple.FontRegis try/

Don't try and edit anything in here yourself. Use the command below to clear font cache files.

Close all running applications. From an administrator account, open the Terminal app and enter the following command. You can also copy/paste it from here into the Terminal window:

sudo atsutil databases -remove

This removes all font cache files. Both for the system and all user font cache files. After running the command, close Terminal and immediately restart your Mac.

Great feedback Kurt Lang, thanks for the clarrification and insight. I would give you a green star if I could. 😁