What does Windows error code 4404 (ERROR_APP_DATA_REBOOT_REQUIRED) mean?

ERROR_APP_DATA_REBOOT_REQUIRED

Fast Cache has been ReArmed and requires a reboot until it can be updated.

ERROR_APP_DATA_REBOOT_REQUIRED is Win32 error 4404 (0x1134) and belongs to Fast Cache rearm completion.

Where the result appears

• Fast Cache rearm after servicing or policy change.
• An application attempting updates before the rearm takes effect.
• Deployment automation validating cache readiness.
• Post-maintenance startup where pending reboot state remains.

Likely causes

• the cache was rearmed and Windows requires a restart to finish the transition.
• servicing changed low-level cache state that cannot be switched live.
• automation ignored the reboot-required success condition.
• multiple maintenance steps accumulated a pending restart.

Troubleshooting steps

• Record rearm command result and timestamp.
• Record pending reboot indicators and servicing events.
• Record current cache mode before and after restart.
• Record applications still holding cache resources.
• Record whether the restart actually completed rather than hibernated.

What to verify

Verify whether the cache was rearmed and Windows requires a restart to finish the transition. Check rearm command result and timestamp together with pending reboot indicators and servicing events.

Handling, retry, and recovery

Schedule a controlled reboot, preserve user work, and verify cache readiness after a full restart. Repeating update calls before reboot will not complete the pending transition.

Difference from nearby codes

This code is an actionable pending-reboot state, not proof that cached application data is corrupt or missing.

Practical example

Deployment re-arms Fast Cache and immediately runs a write validation.

References

• Microsoft: System Error Codes (4000–5999) — reference for error 4404.
• Microsoft: Storage management — reference for error 4404.
• Microsoft: Troubleshoot data corruption and disk errors — reference for error 4404.