Critical Backup Failure: ServerFaultCode: A specified parameter was not correct.

Issue

This article explains troubleshooting steps to resolve the agentless backup error message:

Critical Backup Failure: ServerFaultCode: A specified parameter was not correct.

Environment

• Datto SIRIS

Cause

This error message can be caused by an issue with the changed block tracker issue on the protected machine.

Resolution

To resolve this issue, reset the changed block tracker on the protected machine by either:

• Resetting the tracking as described in the VMware article: Resetting Changed Block Tracking for VMware vSphere virtual machines (external link).

• Destroying the agent's live dataset and running a new full backup.