Microsoft just fixed the safe mode issues in Windows 11, but the operating system has apparently encountered even more issues with the latest cumulative updates. KB5012643, an optional update with numerous fixes, crashes apps that use certain components of the .NET 3.5 framework.
If you’ve been using Microsoft’s desktop operating system for a long time, you’ve probably noticed .NET Framework. The .NET Framework may appear in Windows Update or during the installation process of certain apps. Many apps rely on the .NET Framework to function properly because it contains a collection of code that developers can call when creating their apps.
Simply put, you only need .NET Framework for certain apps to work. Unfortunately, a cumulative update has apparently broken the .NET Framework integration in the operating system and some apps are now crashing. This happens to those who have installed the KB5012643 for Windows 11 version 21H2.
Previously, some users encountered safe mode and installation issues as well as Blue Screen of Death when installing this particular optional update. As the Feedback Hub posts highlight, there are reports online documenting several issues in the latest Windows 11 update, including a bug where certain .NET 3.5 Framework apps crash.
“We are running an SQL application (client and server on the same system) on Windows 11. It ran smoothly on Windows 7 and Windows 10. After installing Windows 11 update KB5012643, applications no longer start. Apps are working again without any problems after uninstalling the update,” one of the affected users wrote in the Feedback Hub.
Fortunately, this glitch does not affect all .NET 3.5 Framework-based apps. In a new update of a support document Originally published on April 25, Microsoft noted that apps that use certain components, such as Windows Communication Foundation (WCF) and Windows Workflow (WWF) are affected.
We don’t have a list of affected apps, but if you’ve struggled to launch apps on Windows 11, now you know why.
Microsoft wants users to uninstall the update
So if you run into app crashes on Windows 11, as the user described in Feedback Hub and later confirmed by Microsoft, it might be worth removing the patch to see if that makes any difference.
In the updated document, Microsoft’s first workaround recommends manually uninstalling the update. Follow these steps to uninstall the update:
- click on Start button and search Windows Update Settings†
- Windows Update settings window, select View update history†
- Select Uninstall update†
- Find KB5012643 in the list.
- Select the patch and click remove†
Otherwise, the only other solution to try your luck is to re-enable the .NET Framework 3.5 and the Windows Communication Foundation in the Windows Features Settings page. You can also run the following commands to perform this action via terminal:
dism /online /enable-feature /featurename:netfx3 /all dism /online /enable-feature /featurename:WCF-HTTP-Activation dism /online /enable-feature /featurename:WCF-NonHTTP-Activation
With these optional updates, there is always a chance that you will encounter undocumented issues, so we do not recommend optional cumulative or driver updates.
In addition to these issues, users are also reporting other issues including issues with Start, taskbar, USB, and more.