"@font-face encountered unknown error." from IE11 on Windows 10

Question

Since we had our computers upgraded to Windows 10, custom fonts do not work in IE 11. The problem appears to occur in every web site that uses custom fonts. The error in the console is @font-face encountered unknown error.

The same sites render fine in Chrome, Firefox and Edge.

As we are a web development shop, we have to be able to test sites in IE, so this is kind of an inconvenience.

Solution

I know this is quite an old question, but we just ran into this issue and spend couple of hours trying to figure the solution. For others who might run into this issue in the future, we solved it by updating a registry key

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Kernel\MitigationOptions) from enabled (1000000000000) to disabled (2000000000000).

Source: https://github.com/FortAwesome/Font-Awesome/issues/9661

As described in the link above, we were having this problem with IE11 in Win10 box only. Edge was working fine. After updating the registry value, icons started displaying in IE too.

Comments

[DavidPostill]

Possible Stack Overflow duplicate: IE 11: error CSS3111 in my own code, and google.com/fonts doesn't render any fonts

[mhenry1384]

@DavidPostill Thanks. Not so much a dupe as a question posted to the wrong site, I would argue. (the correct one being superuser).

[mhenry1384]

That works. Also requires a reboot.