What does Windows error code 4003 (ERROR_INC_BACKUP) mean?

ERROR_INC_BACKUP

The backup failed. Was a full backup done before?

ERROR_INC_BACKUP is Win32 error 4003 (0xFA3) and belongs to WINS incremental backup.

Where the result appears

• Scheduled incremental WINS database backup.
• Administrative backup after a service change.
• Legacy recovery workflows that depend on a prior full backup.
• Monitoring software interpreting WINS backup events.

Likely causes

• no compatible full backup exists as the base for the incremental set.
• the full backup directory was removed or replaced.
• backup metadata does not match the active WINS database.
• permissions or storage errors made the base backup unreadable.

Troubleshooting steps

• Record path and timestamp of the last full backup.
• Record incremental chain metadata and database generation.
• Record service account permissions on the backup directory.
• Record free space and filesystem errors.
• Record WINS backup event sequence.

What to verify

Verify whether no compatible full backup exists as the base for the incremental set. Check path and timestamp of the last full backup together with incremental chain metadata and database generation.

Handling, retry, and recovery

Create and verify a new full backup before requesting another incremental backup. Do not splice unrelated backup generations into the same recovery chain.

Difference from nearby codes

It specifically points to incremental backup prerequisites, while ERROR_FULL_BACKUP concerns failure to create the full backup itself.

Practical example

A retention job deletes the last full backup but leaves newer incrementals.

References

• Microsoft: System Error Codes (4000–5999) — reference for error 4003.
• Microsoft: Windows Internet Name Service (WINS) — reference for error 4003.
• Microsoft: WINS Management Protocol — reference for error 4003.