Font Book for Mac: Validate fonts in Font Book
When you’re installing fonts, Font Book lists any problems it finds for you to review.
Select a font, then choose File > Validate Font.
In the Font Validation window, click the disclosure triangle next to a font to review it.
A green icon indicates the font passed, a yellow icon indicates a warning, and a red icon indicates it failed.
To resolve font warnings or errors, select the checkbox next to a font, then click Install Checked or Remove Checked.
Tip: To find warnings or errors in a long list of fonts, click the pop-up menu at the top-left corner of the Font Validation window, then choose Warnings and Errors.
Resolve duplicate fonts
Font Book identifies duplicate fonts with a yellow warning symbol in the list of fonts.
Choose Edit > Look for Enabled Duplicates.
Click an option:
Resolve Automatically: Font Book disables or moves duplicates to the Trash, as set in Font Book preferences.
Resolve Manually: Continue to the next step to review and handle duplicates yourself.
Examine the duplicates and their copies, then select a copy to keep.
The copy that Font Book recommends keeping is labeled “Active copy” and is selected. To review other copies, select one.
Resolve the current duplicate or, if there is more than one, all duplicates.
If you want the inactive copies to go in the Trash, select “Resolve duplicates by moving duplicate font files to the Trash.”
If you can’t resolve font problems, go to the Apple Support website: Apple Support website.