Clear Font Caches & Font Databases in Mac OS X to Resolve Unusual Font Problems
In some unusual and admittedly rare situations, fonts in OS X and various Mac apps may display erroneously, or outright fail to display. Typically this happens after a font has been modified or a font has been installed outside of the standard ~/Library/Fonts directory, but it can happen out of the blue in some situations as well. While some font issues can be fixed by repairing permissions, more obscure issues may require you to dump the font caches and rebuild them.
This is not something you should do casually as there is no reason to perform this task unless you have very specific font problems pertaining to caches, errors, or specific display errors where glyphs show up rather than fonts.
How to Clear Font Databases & Font Caches in OS X
From the Terminal, enter the following command string and hit return. This uses sudo, which requires the an administrator password to execute, as usual with a command line item you’ll want the command to appear on a single line:
sudo atsutil databases -remove
This will remove all font databases and caches from the OS X system and users. According to the manual page of atsutil, the -remove flag will perform the following:
will remove fontd System or User databases along with any cache
files. Removing databases may cause the loss of font registration state:
fonts activated outside the standard font directories, font faces dis-
abled, and font libraries. New databases will be regenerated from fonts
installed the standard font directories after the user logs out,
restarts, or the fontd server is restarted.
Completing the Font Display Troubleshooting with Permissions & Rebooting
When atsutil has finished running, you will probably want to repair permissions in OS X from the Terminal too by using the disktuil command as well (since you’re already in Terminal, after all):
sudo diskutil repairPermissions /
Repairing disk permissions can take quite some time, so be prepared to wait up to several hours depending on the size and speed of your drive and how many files you have on the Mac.
When both of the above processes are finished, go ahead and reboot the Mac as usual, your fonts should now work and display fine without any further issues.
In case you’re wondering, this image is an example of what such a font display problem may look like:
Obviously if every font on your Mac is displaying like that, as a box with a capital A in it like [A] [A] [A], it may be challenging to do much of anything, and in that case you may need to boot into OS X safe mode, or even into single user mode by holding down Command+S during boot to run the above commands.
Let us know in the comments if this worked for you, or if you have another solution for specific font problems on the Mac.