Synology NAS Error Code 26: How to Fix It

Q: What does Synology Error Code 26 mean?

Synology Error Code 26 means the DSM S.M.A.R.T. scan on one or more of your installed drives has failed. SMART is a monitoring system built into hard drives and SSDs that tracks indicators of drive health. A failed SMART scan indicates the drive reported warning-level or critical-level attribute values, or the test itself could not complete successfully, often signaling hardware degradation.

Q: Is Synology Error Code 26 serious?

Yes, it should be treated as a medium-to-high priority issue. A SMART failure does not always mean the drive will fail immediately, but it is a strong early warning sign. Some drives continue to function for weeks after their first SMART warning; others fail within hours. Back up your data right away and investigate the root cause without delay.

Q: Can I fix a SMART failure without replacing the drive?

Sometimes. If the SMART failure was caused by a loose SATA connection, outdated firmware, or a one-time read error, reseating the drive or updating firmware may clear the issue. However, if critical SMART attributes such as Reallocated Sector Count or Uncorrectable Sector Count are elevated, the physical drive media is degrading and the drive should be replaced — no software fix can repair bad sectors on aging hardware.

Q: Will my data be lost when I replace a failing drive on Synology NAS?

If your NAS uses a redundant RAID configuration (such as SHR, RAID 1, RAID 5, or RAID 6) and only one drive has failed, your data should remain intact. You can replace the bad drive and DSM will rebuild the volume automatically. However, if you are using RAID 0, Basic, or JBOD, there is no redundancy and drive failure means data loss — which is why backups are essential regardless of your RAID setup.

Q: How do I prevent Synology SMART scan failures in the future?

Enable scheduled SMART tests in Storage Manager > HDD/SSD > Settings, set up email or push notifications in Control Panel > Notification, keep DSM and drive firmware updated, use drives from Synology's official Compatibility List, ensure your NAS has adequate ventilation to avoid overheating, and connect your NAS to a UPS to protect against sudden power loss — all of which are leading causes of premature drive failure.

Abstract

Synology NAS Error Code 26 indicates that the DSM (DiskStation Manager) S.M.A.R.T. (Self-Monitoring, Analysis, and Reporting Technology) scan has failed on one or more of your installed drives. This scan is a built-in health check that monitors the condition of your hard drives or SSDs, and a failure means DSM could not complete or pass that check — often signaling a drive that is degrading, unresponsive, or experiencing hardware issues. Addressing this promptly is important because an ignored SMART failure can lead to data loss if the affected drive continues to deteriorate.