Windows 7 Exception in WPF Fonts.SystemFontFamilies After Installing KB4055532

by Avatar Bill Henning (Actipro) - 6 comments
Thursday, January 11, 2018 at 12:30pm

The Microsoft .NET Framework January 2018 Security and Quality Rollup that was released on January 9, 2018 contains a big mistake that causes any calls to Fonts.SystemFontFamilies to immediately throw an exception. 

This affects some of our UI control products, many other third party apps, and possibly your own code as well since that API is a commonly-used .NET property.

The problem doesn't seem to occur on Windows 10, but does occur on Windows 7 systems that have installed the rollup.


The exception message that appears is something like:

No FontFamily element found in FontFamilyCollection that matches current OS or greater: Windows7SP1

With stack trace:

at System.Windows.Media.Fonts.get_SystemFontFamilies()


The only workaround at the moment until it is fixed by Microsoft appears to be to uninstall the KB4055532 rollup on Windows 7 machines.

We expect this to be resolved by Microsoft quickly since posts about it are popping up all over the Internet:

Update:  Official thread from Microsoft acknowledging it and providing a temporary workaround (thanks Stéphane):

Update 2:  Microsoft appears to have released an updated patch that should resolve the fonts issue.

Tags: wpf

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Comments (6)

Posted 6 years ago by keepITcool - Amsterdam
Yep. had a 'few' enquiries in the past days. And found a temporary workaround until M$ fixes this blunder. The error seems to be caused by a mistake in the (xml) file: GlobalUserInterface.CompositeFont Pre update mine were dated 12-07-2017 Post update mine were dated 22-09-2017 Get a copy of the pre-update version... Rename the newer files and copy the old file to the following folders: C:\Windows\Microsoft.NET\Framework\v4.0.30319\WPF\Fonts C:\Windows\Microsoft.NET\Framework64\v4.0.30319\WPF\Fonts works for me.
Posted 6 years ago by keepITcool - Amsterdam
ps: the Cumulative Rollup includes the actual culprit KB4055002
Posted 6 years ago by BLANC Stéphane - Staubli Robotics Suite Product Manager, STAUBLI
Microsoft released an official statement about this issue here (includes workarounds):
Posted 6 years ago by JesperTreetop
Microsoft released a statement of acknowledgement with workarounds:
Posted 6 years ago by Jim Foye
Thanks for the heads-up! I have multiple apps crashing because of this and I had no idea why.
Posted 6 years ago by Bill Henning (Actipro) - Actipro Software LLC
It sounds like Microsoft released an updated patch to resolve this:

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