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[SITUATION] · [QUIET] · [TECHNOLOGY]

2 clusters · 7 sources · 2 days · First seen 19 days ago · Last updated 17 days ago

Microsoft .NET Framework software regression

Overview

Following the August 2026 cumulative update for the .NET Framework, a technical regression was identified affecting applications utilizing the Windows Presentation Foundation (WPF). The issue specifically impacts the printing process and the generation of PDF or XPS documents when certain common fonts, such as Calibri, are used during glyph subsetting.

Microsoft later confirmed that the bug triggers a ‘System.IO.FileFormatException’ across various operating systems, including Windows 10, Windows 11, and Windows Server versions from 2012 to 2025.

A temporary workaround has been provided by enabling the ‘AppContext’ switch ‘MS.Internal.TtfDelta.DisableCmapAndSbitOverflowProtection’ in application configuration files. However, Microsoft cautioned that this bypass disables security protections included in the August update, potentially leaving systems vulnerable. The company advises that this measure should only be used temporarily and when absolutely necessary.

Entities

.NET Framework · Microsoft · Windows Presentation Foundation · Windows

Timeline

17 days ago

[TECHNOLOGY] 5 sources
Microsoft confirms printing and PDF export errors in WPF applications
Microsoft confirmed an August 2026 .NET Framework update bug causing printing and PDF export failures in WPF-based applications across Windows 10, 11, and various Windows Server versions.
19 days ago

[TECHNOLOGY] 2 sources
Microsoft updates Windows Update controls and addresses .NET Framework errors
Microsoft updates Windows Update controls for better scheduling, while a .NET Framework regression causes printing and PDF errors in WPF-based applications using specific fonts.

Sources

infoq.cn · informaticien.be · it-daily.net · ithome.com · programmez.com · soluzionecomputer.it · tomshw.it