GoKawiilMicrosoft's August 2026 .NET update breaks printing and PDF export in WPF apps
Microsoft has confirmed that the August 2026 .NET Framework cumulative update causes some WPF-based applications to throw a System.IO.FileFormatException when printing or exporting to PDF/XPS with fonts like Calibri. The bug affects current Windows 10 and 11 releases as well as Windows Server versions from 2012 through 2025, and Microsoft is still working on a permanent fix.
GoKawiil's interpretation of the reporting above, not reported fact.
Businesses relying on WPF desktop apps for document generation or printing could see workflows disrupted until Microsoft ships a real patch. The only current workaround requires disabling a security protection added in the same update, forcing IT teams to choose between functionality and staying protected against vulnerabilities patched this month.
- August 2026 .NET Framework update breaks printing/PDF export in WPF apps using certain fonts
- Affects Windows 10, 11, and Windows Server 2012–2025
- Temporary workaround disables a security fix from the same update, so should be used sparingly
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Published there as: “Microsoft: August updates break printing, PDF export in WPF apps”
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