Troubleshooting STC failure occurred mid transfer. stcx.SnapshotError: Snapshot returned error code -87 for STC

Scope

This article describes that cause and possible solutions for the error STC failure occurred mid transfer. stcx.SnapshotError: Snapshot returned error code -87 for STC.

IMPORTANT  Shadowsnap is now End of Support. Please migrate from the shadowsnap agent to the latest compatible Datto Windows Agent or Agentless solution. For information on this process, please refer to: How to move from ShadowSnap to the Datto Windows Agent

Cause

• The error code -87 is an official Microsoft System Error Code for "The parameter is incorrect."
• Third-party VSS-aware applications can block access to the Windows VSS writers, and cause this error.

Solution

• Make sure that any incompatible VSS-aware applications are not running on the protected server.
• The following backup services are specifically known by Datto to cause Error Code -87 to populate:
• Backup Agent
• Backup Extender
• Backup Updater

If these services are running on the production machine, disable them to prevent future conflicts.