Uninstall Windows 11 KB5012643 if it crashes your apps
Microsoft just fixed safe mode issues in Windows 11, but the operating system apparently ran into other issues with the latest cumulative updates. KB5012643, which is an optional update with tons of fixes, crashes applications that use certain .NET 3.5 framework components.
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 applications. Many applications rely on .NET Framework to function properly because it includes a collection of code that developers can call upon when building their applications.
Simply put, you just need .NET Framework for some apps to work. Unfortunately, a cumulative update apparently broke the integration of .NET Framework into the operating system and some applications are now crashing. This happens to those who have installed KB5012643 for Windows 11 version 21H2.
Previously, some users were experiencing safe mode and installation issues as well as the blue screen of death when installing this particular optional update. As the Feedback Hub posts point out, there are reports online documenting various issues in the latest Windows 11 update, including a bug where some .NET 3.5 Framework apps crash.
“We are running a SQL application (client and server on the same system) on Windows 11. It worked without issue on Windows 7 and Windows 10. After installing Windows 11 update KB5012643, applications no longer start. Apps work smoothly again after uninstalling the update,” noted one of the affected users in the Feedback Hub.
Fortunately, this problem does not affect all applications based on .NET 3.5 Framework. In a new update to a support document originally released on April 25, Microsoft noted that applications using certain components like Windows Communication Foundation (WCF) and Windows Workflow (WWF) are affected.
We don't have a list of affected apps, but if you're having trouble launching apps on Windows 11, now you know why.
Microsoft wants users to uninstall the update
So if you're experiencing app crashes on Windows 11, as the Feedback Hub user described and later confirmed by Microsoft, it might be worth uninstalling the fix to see if that makes a difference.
In the updated document, Microsoft's first workaround recommends removing the update manually. To uninstall the update, follow these steps:
- Click on Start button and seek Windows Update Settings.
- Windows Update settings window, select View update history.
- To select Uninstall update.
- Find KB5012643 in the list.
- Select the patch and click Uninstall.
Otherwise, the only other solution is to try your luck by re-enabling .NET Framework 3.5 and Windows Communication Foundation on the Windows Feature Settings page. You can also run the following commands to perform this action through the 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 and that is why we do not recommend optional cumulative or driver updates.
In addition to these problems, users also report other issues including issues with startup, taskbar, USB, and more.