What does Windows error code 5912 (ERROR_CLUSTER_INTERNAL_INVALID_FUNCTION) mean?

ERROR_CLUSTER_INTERNAL_INVALID_FUNCTION

An internal cluster error occurred. A call to an invalid function was attempted.

ERROR_CLUSTER_INTERNAL_INVALID_FUNCTION is Win32 error 5912 (0x1718) and belongs to Failover clustering internal cluster function dispatch.

Troubleshooting steps

• Record cluster service version and patched state.
• Record exact operation and call time.
• Record cluster log and service dump if produced.
• Record recent extension, resource DLL, or management changes.

What to verify

Verify whether cluster code attempted to call an invalid internal function. Check cluster service version and patched state together with exact operation and call time.

Handling, retry, and recovery

Treat the result as an internal defect or corruption signal, collect logs and dumps, validate binaries, and avoid repeated configuration changes.

Practical example

A resource extension triggers an invalid internal dispatch.

References

• Microsoft: System Error Codes (4000–5999) — reference for error 5912.
• Microsoft: Failover clustering documentation — reference for error 5912.
• Microsoft: Get-ClusterLog — reference for error 5912.
• Microsoft: Troubleshoot unexpected cluster failover — reference for error 5912.