SIRIS, ALTO, and NAS: Error: Backup failed because backup image files have not been decrypted



When you try to start a backup for an encrypted system protected by a Datto SIRIS (virtual or physical) or a Datto ALTO XL appliance, you receive the error message, "Backup failed because backup image files have not been decrypted."


  • Datto SIRIS
  • Datto ALTO XL
  • Datto Windows Agent
  • Datto Linux Agent
  • Datto Mac Agent
  • Agentless Backups


To ensure the security of your data on encrypted agents, your Datto appliance does not cache your encryption key. As a result, when your device reboots, decrypted agents will automatically re-seal. This error is a result of an encrypted missing a backup because it was not unsealed by a device operator after a reboot of the Datto appliance. 


1. Access the Datto appliance.

2. Navigate to the Protect page. Sealed agents will display the notification shown in Figure 1.

Figure 1: Sealed backup agent (click to enlarge)

3. Select the Decrypt now box for the impacted agent, and enter its encryption passphrase when prompted.

4. Attempt the backup again.

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