HomeWinBuzzer NewsWindows 11 Optional Update Causing Issues for .NET Framework 3.5 Apps

Windows 11 Optional Update Causing Issues for .NET Framework 3.5 Apps

Microsoft says the Windows 11 KB5012643 optional update is causing issues in two .NET Framework 3.5 components.


Microsoft recently rolled out Windows 11 KB5012643 as an optional update. However, the release seems to be causing issues for users. Firstly, it was causing Safe Mode to malfunction, an issue Microsoft has now released mitigation for. However, there is another problem that stems from the optional update.

In an update to the Windows 11 known issues, Microsoft explains KB5012643 is causing problems for apps that use .NET Framework 3.5.

Specifically, apps that have optional Windows components like Windows Workflow (WWF) or Windows Communication Foundation (WCF). Microsoft explains .NET Framework 3.5 apps with these components may stop working after KB5012543 (also known as OS Build 22000.652) is installed.

Microsoft does have a workaround in place to mitigate the issue until a stable fix is released. The company says users should simply uninstall KB5012643 from Windows 11.:

“To mitigate this issue, you can uninstall KB5012643. To do this, select the Start button and type, Windows Update Settings, and select it. On the Windows Update settings window, select View Update History then select Uninstall Update. Find KB5012643 in the list and select it, then select Uninstall.”

Other Option

If the update will not uninstall, Microsoft says users can take the advanced mitigation route and re-enable .NET Framework 3.5 and the components.

However, this requires running the following commands in an elevated command prompt:

dism /online /enable-feature /featurename:netfx3 /all
dism /online /enable-feature /featurename:WCF-HTTP-Activation
dism /online /enable-feature /featurename:WCF-NonHTTP-Activation

I don’t advise taking this mitigation path unless you are confident playing around with your Windows system. Microsoft is currently classing this issue as “mitigated” but a permanent fix is in the works and should be released shortly.

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Luke Jones
Luke Jones
Luke has been writing about all things tech for more than five years. He is following Microsoft closely to bring you the latest news about Windows, Office, Azure, Skype, HoloLens and all the rest of their products.

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