QNAP NAS Error Code 55: How to Fix It

Medium 30-90 minutes Medium Severity Verified June 2026
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Error Code
55
Brand
QNAP
Product Type
nas
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
30-90 minutes
QNAP NAS Error Code 55 indicates that a Snapshot Replica job has failed, meaning your NAS was unable to successfully copy or synchronize a volume or LUN snapshot to a remote destination. This can happen due to network interruptions, storage space shortages, misconfigured replication settings, or firmware/software inconsistencies. While your data is not immediately lost, this error means your off-site or secondary backup copy is out of date and should be resolved promptly to maintain data protection.
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How to Fix Error Code 55

  1. Check the Snapshot Replica Job Log

    Do not delete or reconfigure the replication job before reviewing the logs, as you may lose diagnostic information needed to identify the exact cause.

  2. Verify Network Connectivity to the Target NAS

    If you are replicating over the internet, ensure that the required ports (default: TCP 8080 or 443 for QNAP replication) are open on both sides of the firewall.

  3. Confirm Sufficient Storage Space on the Target NAS

  4. Check and Re-authenticate the Replication Job Credentials

    Use a dedicated replication user account with limited privileges on the target NAS rather than the full admin account, to follow security best practices.

  5. Update QTS Firmware on Both NAS Devices

    Always back up your NAS configuration (Control Panel > Backup/Restore > Configuration Backup) before performing a firmware update. Ensure the NAS stays powered during the update process.

  6. Check Source Volume and Snapshot Health

    If any drive shows a SMART warning or error, back up all data immediately before performing any further troubleshooting. A failing drive can lead to data loss.

  7. Delete and Recreate the Replication Job

    Before deleting the old job, note all its settings (schedule, source, target, retention policy) so you can recreate it accurately.
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When to Call a Professional

Contact QNAP technical support or a qualified IT professional if: your storage pool is reporting errors you cannot resolve, multiple drives are showing SMART failures, you suspect data corruption on the source or target volume, your NAS is under active warranty, or you are unable to restore successful replication after completing all troubleshooting steps. If this NAS holds critical business data, a certified data recovery specialist or NAS administrator should be consulted before making further changes.

Frequently Asked Questions

What does QNAP Error Code 55 mean?
QNAP Error Code 55 means that a Snapshot Replica job has failed. This is the process that copies snapshots from one NAS to another for backup or disaster recovery purposes. The error indicates that the replication did not complete successfully, leaving the remote copy out of date.
Will I lose my data if Error Code 55 appears?
No, Error Code 55 does not mean your data on the source NAS is lost. Your original files and local snapshots remain intact. However, your remote replica is no longer current, which means your off-site backup protection is reduced until the issue is resolved.
How do I manually trigger a Snapshot Replica job on QNAP?
Log into the QTS interface, go to Storage & Snapshots > Snapshot > Snapshot Replica, locate the replication job, and click the Run Now button. This forces an immediate replication attempt outside of the scheduled window, which is useful for testing after you have made changes.
Can a full storage pool cause QNAP Snapshot Replica Error Code 55?
Yes. If the target NAS storage pool is full or nearly full, the incoming snapshot data cannot be written, and the replication job will fail with Error Code 55. Always ensure the destination NAS has at least 20% free space available in the storage pool used for replication.
Does the QNAP firmware version affect Snapshot Replica?
Yes, running different or outdated firmware versions on your source and target NAS devices is a known cause of replication failures including Error Code 55. QNAP recommends keeping both units on the same latest stable firmware version to ensure full compatibility between their replication protocols.

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