How to Fix Windows Stop Code 0xc000021a (BSOD)
Quick Fix Summary
TL;DRBoot from Windows installation media and run Startup Repair, then use System Restore to revert to a known-good configuration.
The STATUS_SYSTEM_PROCESS_TERMINATED error occurs when a critical user-mode subsystem (like Winlogon or Csrss.exe) fails unexpectedly. This is a fatal system error that halts Windows to prevent data corruption.
Diagnosis & Causes
Recovery Steps
Step 1: Boot to Advanced Startup & Run Startup Repair
Use Windows Recovery Environment (WinRE) to attempt an automatic fix. This is the fastest path to recovery if the system can access WinRE.
# Force restart into WinRE (if system partially boots)
shutdown /r /o /t 0
# OR Boot from Windows Installation USB, select 'Repair your computer'Step 2: Perform a System Restore
Revert the OS state to a point before the error appeared. This is highly effective for software/driver-induced crashes.
# From WinRE Command Prompt, list available restore points
rstrui.exe /offline:C:\windows
# Follow GUI prompts to select a recent restore point.Step 3: Scan & Repair System Files Offline
Use Deployment Imaging Service and Management Tool (DISM) and System File Checker (SFC) from WinRE to fix corrupted core files.
# From WinRE Command Prompt, identify Windows partition
diskpart
list volume
exit
# Assume Windows is on D:
DISM /Image:D:\ /Cleanup-Image /RestoreHealth
sfc /scannow /offbootdir=D:\ /offwindir=D:\windowsStep 4: Check & Repair Boot Configuration
Rebuild the BCD (Boot Configuration Data) which may be corrupted, preventing critical processes from loading.
# From WinRE Command Prompt (Windows on D:)
bootrec /fixmbr
bootrec /fixboot
bootrec /scanos
bootrec /rebuildbcdStep 5: Clean Boot or Last Known Good Configuration
If you can reach the Advanced Boot Options menu, try loading a minimal driver set or the last working configuration.
# Restart and press F8 (or Shift+Restart) for Advanced Options
# Select 'Last Known Good Configuration'
# OR Select 'Safe Mode' to uninstall recent software/drivers.Step 6: Manual Registry Repair (Advanced)
If a specific hive is damaged, replace it with a backup from the RegBack folder. This requires another working Windows instance.
# From WinRE CMD, copy backup hive (e.g., SOFTWARE)
# Backup the corrupted hive first
copy D:\windows\system32\config\software D:\windows\system32\config\software.bad
# Restore from RegBack
copy D:\windows\system32\config\RegBack\software D:\windows\system32\config\Architect's Pro Tip
"Before major updates or driver installs, create a manual system restore point and export the 'SYSTEM' and 'SOFTWARE' hives via regedit. This gives you a clean rollback target."
Frequently Asked Questions
Will I lose my data fixing this error?
The fixes (Startup Repair, System Restore, SFC) are non-destructive to user data. However, severe corruption may require a repair install or clean install, where backing up data first is crucial.
What's the difference between 0xc000021a and other BSODs?
Error 0xc000021a specifically indicates a critical user-mode process crash (Winlogon, Csrss), making the system unstable. Other BSODs typically involve kernel-mode drivers.
How can I prevent this error in the future?
Maintain regular system image backups, install updates in stages, use driver verifier for new drivers, and run periodic SFC /scannow checks.