Microsoft’s optional update KB5067036, released on October 28, 2025 for Windows 11 versions 24H2 and 25H2, introduces a regression that prevents Task Manager from terminating cleanly. Closing the Task Manager window does not end the underlying taskmgr.exe process, leading to multiple orphaned instances that accumulate over time and degrade system performance.
Who is affected and how the Windows 11 Task Manager bug manifests
The issue impacts devices that have installed the optional (preview) update KB5067036. When users close Task Manager, the interface disappears but the process persists in the background. Each new launch creates an additional instance instead of reusing or terminating the previous one, allowing dozens of processes to remain resident.
Each lingering taskmgr.exe consumes approximately ~20 MB of RAM and up to ~2% CPU. At scale, this results in noticeable slowdowns, UI freezes, and delayed application launches. Users can verify the condition via Task Manager’s Details tab or by running Get-Process taskmgr in PowerShell to enumerate active instances.
Microsoft response to the KB5067036 Task Manager issue
Microsoft has acknowledged the defect, noting that previous Task Manager instances may continue running invisibly, leading to multiple active taskmgr.exe processes and potential performance degradation. The company is developing a fix; however, it has not provided an ETA for a corrective patch.
Technical analysis: why taskmgr.exe remains after closing
Observed behavior indicates a fault in application shutdown handling. The main window closes, but the process does not receive or correctly process a termination signal, leaving the executable in a background state without a visible window. Subsequent launches spawn fresh processes with their own message loops. In practical terms, this resembles an orphaned foreground UI thread with surviving background threads, explaining the “multiplication” of processes and incremental CPU and memory usage.
Workarounds: how to fix Task Manager not closing on Windows 11
End processes via Task Manager
Open a new Task Manager instance, switch to Details, select all taskmgr.exe entries, and choose End task. This safely clears the accumulated instances.
Force-close with Command Prompt (Administrator)
Run: taskkill.exe /im taskmgr.exe /f. This terminates all active Task Manager processes immediately.
Use PowerShell (Administrator)
Execute: Stop-Process -Name taskmgr -Force. To count instances, use: Get-Process taskmgr | Measure-Object.
Enterprise recommendations: managing KB5067036 risk
– Limit repeated openings of Task Manager until a patch is available. If you must relaunch, ensure all instances are terminated first.
– Implement monitoring and alerting. In EDR (Endpoint Detection and Response) or your monitoring stack, trigger alerts when the count of taskmgr.exe processes exceeds a baseline and when CPU or memory utilization spikes atypically.
– Control preview updates. In production environments, defer or block optional/preview updates (e.g., via WSUS, Intune, or Group Policy) until Microsoft publishes a stable fix and documents resolution in release notes.
– Consider a safe rollback if performance is materially affected. Navigate to Settings → Windows Update → Update history → Uninstall updates and remove KB5067036. Schedule rollbacks during maintenance windows and create a restore point prior to change.
Until Microsoft ships a corrective update, the priority is to monitor and manage taskmgr.exe instance counts to prevent cumulative performance loss. Users should apply the workarounds above and follow Microsoft’s communications on known issues for Windows 11. IT teams should log the incident in change management, enforce a temporary policy to block optional updates in production, and maintain observability for anomalous process proliferation and resource usage.
