Synology NAS Error Code 29: How to Fix It

Medium 2 hours to several days (migration runs automatically; monitoring takes 15-30 minutes of active attention) Medium Severity Verified June 2026
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Error Code
29
Brand
Synology
Product Type
nas
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
2 hours to several days (migration runs automatically; monitoring takes 15-30 minutes of active attention)
Synology NAS Error Code 29 indicates that your device is currently performing a Synology Hybrid RAID (SHR) migration — a process where the RAID configuration of your storage pool is being changed or expanded. This is a normal, expected status message rather than a hardware failure, but it does mean your NAS is performing a critical background operation that should not be interrupted. Understanding what is happening and what you should (and should not) do during this time is essential to protecting your data.
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Tools You'll Need

How to Fix Error Code 29

  1. Confirm the Migration Is Actively Running

    Do NOT power off, restart, or unplug the NAS while migration is in progress. Interrupting SHR migration can result in permanent data loss or a corrupted storage pool.

  2. Check Estimated Completion Time

  3. Ensure Stable Power Supply

    A sudden loss of power during migration may leave the storage pool in an unrecoverable state. A UPS is strongly recommended for all long-running storage operations.

  4. Reduce Load on the NAS During Migration

  5. Monitor DSM Notifications for Errors

    If a drive fails during migration and your pool has no redundancy to spare, data loss is possible. Act immediately on any drive health warnings.

  6. Verify Completion and Check Volume Health

  7. If Migration Appears Stuck or Frozen

    Do not force restart the NAS simply because migration seems slow. Confirm via logs that there is an actual error before taking any action.

Parts You May Need

Replacement hard drive (NAS-rated)
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Uninterruptible Power Supply (UPS)
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Replacement hard drive (NAS-rated)
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Uninterruptible Power Supply (UPS)
Check Price on Amazon
Replacement hard drive (NAS-rated)
Check Price on Amazon
Uninterruptible Power Supply (UPS)
Check Price on Amazon
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When to Call a Professional

Contact Synology technical support or a professional data recovery service if: the migration has been completely frozen with no progress for more than 48 hours and system logs show active errors; one or more drives have failed during the migration and the volume is in a degraded or crashed state; DSM reports the storage pool as 'Crashed' or 'Read-Only' after an unexpected shutdown; or you are unable to access DSM at all. Do not attempt manual RAID recovery tools on a Synology SHR pool without expert guidance, as this can make professional data recovery impossible.

Frequently Asked Questions

How long does Synology SHR migration take?
SHR migration time depends heavily on the total size and number of drives involved. A migration involving 4TB drives can take 12 to 24 hours, while multi-drive pools with 8TB or larger drives can take 2 to 5 days or more. Reducing load on the NAS during migration helps it finish faster.
Is it safe to use my Synology NAS while Error Code 29 migration is running?
You can continue light use of the NAS, such as accessing files or running lightweight services, but it is best to avoid resource-intensive tasks like large file transfers, video transcoding, or backup jobs. Heavy usage slows migration and increases the risk of issues if a drive is under stress.
Can I cancel or stop a Synology SHR migration in progress?
No. Once SHR migration has started, it cannot be safely canceled mid-process. Forcing it to stop by cutting power or restarting the NAS risks corrupting the storage pool and losing all data on it. You must allow the migration to complete fully.
What triggers Synology Error Code 29 SHR migration?
Error Code 29 is typically triggered when you add a new hard drive to an existing SHR storage pool to expand capacity, when you change the RAID type of a volume, or when you replace drives in a pool with larger capacity drives and expand the volume. DSM initiates the migration automatically as part of these operations.
What should I do if a hard drive fails during Synology SHR migration?
Immediately check Storage Manager for the status of the pool. If the pool shows as 'Degraded,' do not panic — SHR is designed to tolerate a single drive failure. Replace the failed drive with a compatible new drive as soon as possible and allow DSM to repair the pool. If the pool shows as 'Crashed,' stop all activity and contact Synology support or a professional data recovery service right away.

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