What does Windows error code 809 (ERROR_FILE_METADATA_OPTIMIZATION_IN_PROGRESS) mean?

ERROR_FILE_METADATA_OPTIMIZATION_IN_PROGRESS

File metadata optimization is already in progress.

ERROR_FILE_METADATA_OPTIMIZATION_IN_PROGRESS is Win32 error 809 (0x329) and belongs to filesystem metadata optimization.

Where the result appears

• A filesystem maintenance request that compacts or reorganizes metadata.
• Volume servicing code coordinating a long-running optimization.
• Administrative tooling polling the state of an optimization job.
• A second caller attempting to start work already owned by another request.

Likely causes

• an earlier metadata optimization has not completed.
• the service or filesystem retained an active operation context after the initiating process disconnected.
• two maintenance tools scheduled overlapping work on the same volume.
• the operation is progressing normally but the caller interpreted the state as a hard failure.

Troubleshooting steps

• Record volume GUID and filesystem type.
• Record identifier and start time of the active optimization request.
• Record maintenance events and filesystem operational logs.
• Record whether the first owner still has a live handle or service job.
• Record free space and I/O latency during the optimization window.

What to verify

Verify whether an earlier metadata optimization has not completed. Check volume GUID and filesystem type together with identifier and start time of the active optimization request.

Handling, retry, and recovery

Do not start a parallel optimizer. Observe the existing operation, wait for its documented completion state, and retry only after the volume reports that no optimization is active.

Difference from nearby codes

The code does not mean that general file metadata is unavailable; it reports serialization of a specific maintenance activity.

Practical example

Two scheduled maintenance tasks overlap after a delayed boot.

References

• Microsoft: System Error Codes (500–999) — reference for error 809.
• Microsoft: File management functions — reference for error 809.