Error code
Windows 0xC000021A
WINDOWS0xC000021A
System Error Code· A POSIX/system errno returned when a system call fails.
What it means
WINLOGON_FATAL_ERROR — the Winlogon (or CSRSS) user-mode subsystem terminated unexpectedly so security can no longer be guaranteed..
How to fix it
- Run sfc /scannow and DISM RestoreHealth from recovery.
- uninstall or disable recently added software drivers or services.
- perform a System Restore to before the issue.
- run Startup Repair.
- reseat or test the system drive.
Not affiliated with Windows. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.
More Windows codes
- 0x0000000AIRQL_NOT_LESS_OR_EQUAL — a kernel-mode driver or Windows accessed paged memory at an invalid address while running at a raised interrupt request level (IRQL).
- 0x00000019BAD_POOL_HEADER — a kernel memory pool header is corrupt.
- 0x0000001AMEMORY_MANAGEMENT — a severe memory management error occurred.
- 0x0000001EKMODE_EXCEPTION_NOT_HANDLED — a kernel-mode program generated an exception the error handler did not catch.
- 0x0000003BSYSTEM_SERVICE_EXCEPTION — an exception occurred while executing a routine that transitions from non-privileged to privileged code.
- 0x0000004AIRQL_GT_ZERO_AT_SYSTEM_SERVICE — a thread returned to user mode from a system call while its IRQL was still above PASSIVE_LEVEL.
- 0x00000050PAGE_FAULT_IN_NONPAGED_AREA — invalid system memory was referenced (a wrong or freed memory address).
- 0x0000005CHAL_INITIALIZATION_FAILED — the Hardware Abstraction Layer failed to initialize during startup.
- 0x0000007BINACCESSIBLE_BOOT_DEVICE — Windows lost access to the system partition during startup.
- 0x0000007ESYSTEM_THREAD_EXCEPTION_NOT_HANDLED — a system thread generated an exception the error handler did not catch.
- 0x0000009FDRIVER_POWER_STATE_FAILURE — a driver is in an inconsistent or invalid power state during a power transition.
- 0x000000A0INTERNAL_POWER_ERROR — the power policy manager experienced a fatal error.