What is 0xC000021A-2?
0xC000021A is a critical-severity Windows operating system problem. A critical user subsystem (such as WinLogon or CSRSS) has been critically terminated. The system cannot continue to run. It's most often caused by incomplete or incorrect installation of update and incompatible third-party software. See the troubleshooting steps below for the fix.
Common Causes
- Incomplete or incorrect installation of update
- Corrupted system registries
- Incompatible third-party software
Step-by-Step Fix Guide
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1
Repair the system with DISM
Most reports of 0xC000021A clear up after Repair the system with DISM, so it's worth trying before anything more involved.
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2
Roll back recent system changes from restore point
Should the issue continue afterward, the remaining steps are there to cover the less common windows instability scenarios.
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3
Turn off driver signature enforcement in Advanced Boot Options
For lingering 0xC000021A-2 cases, "Turn off driver signature enforcement in Advanced Boot Options" is worth running through.
Commands & Diagnostics
DISM /Online /Cleanup-Image /RestoreHealth
sfc /scannow
Frequently Asked Questions
In most cases, incomplete or incorrect installation of update is behind 0xC000021A-2. Corrupted system registries and incompatible third-party software can trigger it too.
Most 0xC000021A-2 reports resolve after "Repair the system with DISM". The rest of the guide above is there for the cases that don't.
Treat 0xC000021A-2 as urgent — it's flagged critical severity, meaning repeated occurrences risk data loss or hardware damage.
In most cases, yes — the guide above resolves 0xC000021A-2 without a clean install. Treat a reinstall as the last resort, not the first move.
Sometimes. Microsoft regularly releases patches that fix known BSOD triggers including 0xC000021A-2. Make sure Windows is fully up to date via Settings → Windows Update before attempting more advanced fixes.
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