SIRIS, ALTO, and NAS: Error: STC failure occurred mid transfer


1. Problem

Backups fail with error:

STC failure occurred mid transfer.

No recent error reported from ShadowSnap agent.


2. Solution

Ensure the ShadowSnap Agent is up to date. Find the latest ShadowSnap version information here.

Follow these steps to solve the problem:

  1. Check the Agent log by clicking the View Backup Logs link and then Show Agent Logs.
Note: In the New UI, you will have to click on Configure and then Legacy Interface in order to get to View Backup Log and Show Agent Log.

  • If you see an error highlighted in red, search the most generic version of that error in the Knowledge Base.

2. Re-protect the agent from the web console. You can also repair agent communications from the Advanced Options tab per agent.

3. Upgrade to the latest version of the agent from this link. Reboot the target machine.
If you are already on the latest version, uninstall all software, reboot, re-install, reboot, and try backing up again.

4. Make sure all three services are running and active:

  • ShadowProtect Service
  • StorageCraft Raw Agent
  • StorageCraft Shadow Copy Provider

5. If the errors persist, force a differential merge from the Advanced Options tab of the Agents page.

6. Test a ShadowProtect backup against a NAS share on the Datto device to determine if ShadowProtect can back up successfully.

3. Cause

  • Many of these transient errors were caused by earlier versions of ShadowSnap and ShadowProtect.
  • Updating to the latest version of both is highly recommended.
  • The latest installer package can always be found at this link. Be advised that a reboot of the target machine may be necessary.

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