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WINLOGON_FATAL_ERROR
Winlogon fatal error for WINLOGON_FATAL_ERROR
WINLOGON_FATAL_ERROR is bug check code 0xC000021A.
Microsoft documents this as one of the few cases where a user-mode subsystem failure can shut down Windows, because Winlogon and CSRSS are required for the operating system to run securely.
How to read it in a dump
- The real failure is often in user mode, so a kernel debugger alone may not identify the initiating application or service.
- Mismatched or restored system files, third-party services, credential components, or subsystem compromise can be involved.
- The dump and event logs should identify whether Winlogon, CSRSS, or a dependent component terminated first.
What to check
- Check recent service, driver, security, credential-provider, and system-file changes.
- Collect user-mode dumps or event logs for Winlogon/CSRSS-related failures when available.
- Verify system file consistency and restore provenance before reinstalling or replacing random binaries.
References
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