A bizarre Windows 11 bug duplicates Task Manager instead of closing it

If you’re a Windows 11 user who frequently uses the Task Manager tool, you should probably avoid Microsoft’s latest OS update. Reddit users and my colleague Tom Warren are reporting that a bug in the optional Windows 11 KB5067036 update is causing Task Manager to duplicate itself when they attempt to close the app, impacting computer performance.

The bug is breaking the “X” button to quit Task Manager, preventing the app from shutting down and instead keeping it running in the background. Repeated attempts to open and close the app result in multiple instances that can eat up your CPU and RAM resources.

Microsoft has acknowledged the problem in a support page, saying that the issue “results in multiple lingering instances of taskmgr.exe, consuming system resources and potentially degrading device performance.” Microsoft says “we are working on a resolution for this issue and will provide more information when it is available.”

Thankfully, Windows Latest and Reddit user BNSoul have found a temporary workaround. Individual Task Manager instances can be closed by selecting the “End task” button on the app instead of clicking the “X” button, or users can run taskkill /im taskmgr.exe /f in the Windows 11 Command Prompt to shut down all of the Task Manager instances simultaneously. Microsoft recommends these mitigations as well.

Update, October 31st: Added details from Microsoft.