ALERT: Datto Drive Cloud service will no longer be available as of July 1, 2019. For more information, see our end-of-life article. If you'd like to migrate your data to Datto Workplace, see our migration guide.
To learn how to download your Datto Drive Cloud data, please visit this article.

[Errno 22] STC Failure Occurred Mid-Transfer



This article discusses the cause and potential resolutions of the "Errno 22 Invalid Argument" ShadowSnap backup error.


This error may be triggered during backup job initialization when the ShadowSnap software on a protected machine cannot properly access files shared through the Samba protocol by the Datto device to transfer backup job metadata.

This error may also occur on encrypted agents before data transfer is initiated over iSCSI.


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

Restarting Services

Restart the following services on the protected machine:

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

Force a new backup. If the backup fails, continue with the steps below.

Share Compatibility Mode

Enable "Share Compatibility Mode" for the agent

  • Log in to the Datto device's web interface.
  • Click the Protect tab in the main menu bar at the top of the page.
  • Click the Configure Agent Settings link for the agent experiencing the error.
  • Click on the Share Compatibility Mode link in the menu on the left-hand side of the screen. This will cause the right-hand side of the screen to shift to the Share Compatibility Mode section
  • Enable Share Compatibility Mode: Click the Share Compatibility Mode check box.
  • Force a backup of the agent from the Protect tab.
  • If the backup continues to fail, proceed to the next step.

Reinstall the ShadowSnap Agent

  • If the preceding steps did not resolve the error, uninstall and reinstall the Shadow Snap agent on the server by following the process in the Reinstalling the ShadowSnap Software article.

If you are unable to resolve the issue using the steps in this article, please contact Datto Technical Support.

Was this article helpful?

0 out of 4 found this helpful

You must sign in before voting on this article.

Want to talk about it? Have a feature request?

Head on over to our Community Forum or get live help.