By Richard Speed
Publication Date: 2026-08-25 11:27:00
OS PLATFORMS
Summer in Redmond, Winter for everyone else
Having some unexpected printer problems? Microsoft’s August 2026 .NET update might have broken printing on your device.
According to Microsoft, “After installing the August 2026 .NET Framework cumulative update, some WPF applications may fail with a System.IO.FileFormatException when printing or generating PDF/XPS content that uses certain fonts, including Calibri.”
Ah yes, Calibri, the default font in some versions of that little-used application, Microsoft Word.
The cumulative update for .NET Framework released on August 11 came jam-packed with fixes, but also printer problems afflicting the company’s client operating systems (Windows 10 and 11) and Windows Server 2012 through 2025.
Microsoft’s workaround is a tweak in the app config file to enable Switch.MS.Internal.TtfDelta.DisableCmapAndSbitOverflowProtection. However, as the company notes,…
