Microsoft’s August Patch Tuesday Update Breaks Printing and PDF Export in Some Apps
A critical issue has emerged with Microsoft’s recent .NET Framework update, which is causing problems for users trying to print or export documents as PDFs in certain applications. The affected software includes apps that rely on the Windows Presentation Foundation (WPF) UI framework, a widely-used tool for building Windows desktop client applications.
Microsoft’s latest Patch Tuesday update was intended to fix various security vulnerabilities and improve overall system stability. However, it appears that this update has introduced an unintended consequence: some WPF-based applications are now failing when users attempt to print or generate PDF content. This is especially true for documents using fonts such as Calibri, which are commonly used in business settings.
The problem affects not only consumer versions of Windows but also server platforms, including the latest releases of Windows Server 2012 through 2025. Microsoft is still investigating the issue and working on a permanent solution, but until then, users can try to work around the problem by enabling a specific AppContext switch in their application config file.
This workaround involves adding a small code snippet to the app’s configuration settings. However, it’s essential to note that doing so will disable certain security protections introduced with this month’s update. This means that users who employ this temporary fix may inadvertently leave themselves more vulnerable to attacks that exploit vulnerabilities addressed by the recent security patches.
Microsoft has warned users not to rely on this workaround indefinitely and to use it only when absolutely necessary to address the printing issue. The company is urging developers of affected applications to take steps to mitigate the problem, which could involve updating their software to work around the bug.
For individual users, the best course of action is to wait for Microsoft’s permanent fix or consider using alternative apps that don’t rely on WPF. In the meantime, those experiencing issues with printing and PDF export should try using a different font in their documents or exploring other workarounds until a more comprehensive solution is available.
Ultimately, this incident serves as a reminder of the complexities involved in software updates and the importance of thoroughly testing patches before they are released to the public. As Microsoft continues to investigate and address this issue, users can take steps to minimize their exposure by being cautious when applying updates and seeking out reliable information on workarounds and fixes.
Source: Bleeping Computer — 2026-08-24