Task Manager Won’t Close on Windows 11? Check for Hidden Taskmgr.exe

Windows 11 Task Manager interface with a padlock symbol, suggesting hidden background processes and performance impact.
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Is Task Manager Really Closed?

Task Manager looks closed, but your PC still feels slow? You’re not imagining things. There was a real Windows 11 issue where Task Manager didn’t fully exit when you clicked the X—and in some cases, it could even stack multiple hidden Task Manager processes in the background. This happened on specific builds tied to an optional preview update (KB5067036). The good news: Microsoft marked the issue as resolved in a later update. If you’re still seeing it today, the fix is usually straightforward: confirm your update level, remove the extra Task Manager instances, and install the newer cumulative update.

TL;DR (Quick Fix)

    • Check if you installed KB5067036: Settings → Windows Update → Update history
    • Check for duplicates: Task Manager → Details → look for multiple Taskmgr.exe
    • Kill all Task Manager instances: Run taskkill /im taskmgr.exe /f (Admin)
    • Install the latest cumulative update: It contains the fix on supported builds
If you want the exact “why” + clean step-by-step verification, keep reading.

1) What Happened: The “Immortal Task Manager” Bug

KB5067036 was a non-security optional preview update released for Windows 11 version 24H2 and 25H2. Reports showed that after installing it, clicking the X to close Task Manager could leave it running invisibly in the background. Reopening Task Manager could then create another instance, causing multiple Taskmgr.exe processes to accumulate and waste CPU/RAM over time. ger process might continue to run in background after app is closed”, tied to KB5067036, and marked it as resolved in a later update.

2) First: Confirm Whether You Installed KB5067036

    1. Open Settings (Win + I).
    1. Go to Windows Update → Update history.
    1. Look for an entry that mentions KB5067036 (it may be listed under “Quality updates” or similar).
If you don’t see KB5067036, you can still follow the diagnostics in this article—because “Task Manager is closed but PC is slow” can also be caused by indexing, Defender scans, driver issues, or a stuck process. But the “duplication” symptom is strongly associated with that preview update.
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3) Quick Test: Does Task Manager Really Close on Your PC?

Let’s run a simple repeatable test that takes 30 seconds.
    1. Open Task Manager with Ctrl + Shift + Esc.
    1. Open the Details tab.
    1. Sort by Name and find Taskmgr.exe.
    1. Count how many Taskmgr.exe entries you see.
    1. Close Task Manager using the X.
    1. Wait 5–10 seconds.
    1. Open Task Manager again (Ctrl + Shift + Esc) and re-check the Details tab.
Expected behavior: You should see only one Taskmgr.exe while Task Manager is open, and zero after it’s closed. If you’re affected: The number of Taskmgr.exe entries can increase each time you open/close Task Manager, because older instances stay hidden in the background.

4) Fix: Safely Remove the Hidden Task Manager Processes

If you see multiple instances, you can clean them up immediately. This does not harm Windows—it simply forces Task Manager to exit properly.

Method A (Recommended): Command Line (Most Reliable)

    1. Press Win + X → choose Windows Terminal (Admin) (or Command Prompt as admin).
    1. Run this command:
taskkill /im taskmgr.exe /f
All Task Manager instances (including hidden ones) will close. Then reopen Task Manager with Ctrl + Shift + Esc and confirm there’s only one Taskmgr.exe.

Method B: End Task from the GUI

    1. Open Task Manager.
    1. Go to Details.
    1. Right-click extra Taskmgr.exe entries → End task (leave one if you want to keep the window open).
This works, but the command-line method is faster when many instances piled up.

5) The Real Fix: Install the Update That Resolves It

Killing the extra processes removes the immediate slowdown, but the best solution is to install the newer cumulative update that contains the fix for the background Task Manager issue. Microsoft lists the issue as resolved in Release Health, and coverage of the following cumulative update notes that the Task Manager problem was fixed.
    1. Open Settings → Windows Update.
    1. Click Check for updates.
    1. Install the latest cumulative update offered.
    1. Restart when prompted.
If you’re on a managed PC (work/school), you may need to wait for IT to approve it—so use the cleanup command in the meantime if the processes keep multiplying.

6) Still Slow After an Update? Check These Common “Hidden Load” Causes

Even without the Task Manager bug, Windows often runs heavy background work after large updates. This can temporarily make your PC feel sluggish.

A) Windows Search Indexing

After updates or big file changes, Windows may rebuild its search index. This can cause increased CPU or disk activity for a while.

B) Microsoft Defender Scans

Defender may run longer scans after updates or definition changes, especially on laptops with slower storage.

C) A Stuck Process or Shell Component

If Explorer or Start feels “laggy,” a shell process might be struggling after the update. A clean restart often helps.

7) Tools to Diagnose What’s Really Using CPU/Disk

7.1 Resource Monitor (Best for Disk + CPU details)

    1. Press Win + R, type resmon, press Enter.
    1. Check the CPU and Disk tabs.
If a process is constantly active for a long time (not just a few minutes), that’s a better lead than guessing.

7.2 Reliability Monitor (Easy timeline of failures)

    1. Open Start and search Reliability Monitor (or “View reliability history”).
    1. Click the day the slowdown started.
    1. Look for repeated “Windows failure” or “Application failure” entries.
This is one of the fastest ways to see whether the system is quietly crashing in the background.

8) Should You Uninstall KB5067036?

Because KB5067036 was an optional preview update, uninstalling it is a reasonable choice if it clearly caused problems and you can’t install the resolved cumulative update yet.

When uninstalling makes sense

    • The duplication keeps coming back repeatedly
    • Your PC is a work machine and stability matters more than preview features
    • You can’t install the newer update that includes the fix yet

How to uninstall

    1. Settings → Windows Update → Update history
    1. Select Uninstall updates
    1. Find KB5067036 → click Uninstall
    1. Restart the PC
After uninstalling, keep Windows Update enabled so you can install the next stable cumulative update that supersedes the preview build.

9) Prevention: Smart Update Habits for a Stable PC

    1. Treat preview updates as optional. Install them only if you need a specific fix or feature.
    1. Keep startup apps minimal. Fewer background utilities = fewer surprises after updates.
    1. Give Windows idle time after updates. Indexing and security scans often settle down after a while.
    1. When something feels off, check logs first. Reliability Monitor and Resource Monitor save hours of guessing.

10) Summary

    • KB5067036 (optional preview) triggered reports where Task Manager didn’t fully close and could create multiple background instances.
    • You can confirm the issue by checking Details → Taskmgr.exe count after opening/closing.
    • Immediate cleanup: taskkill /im taskmgr.exe /f　(Only needed if duplicate Task Manager processes remain.)
    • Best fix: install the newer cumulative update that resolves the issue (listed as resolved in Release Health).
    • If you can’t update yet and need stability, uninstalling the preview update is reasonable.

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