70255: Acronis Cyber Protect: Hyper-V VM backup fails with "Unexpected call result. Error code 32768"

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Operating Systems: 

Last update: 16-03-2022


  • You are backing up a Hyper-V virtual machine in agentless mode,
  • Backup fails with the following error:

    Unexpected call result. Error code 32768



The most frequent root cause are VSS issues in the guest operating system.


If there is an SQL Server installed on the virtual machine:

Repair the SQL instance on the guest VM:

  1. Go to Control panel -> Programs and features
  2. Find the SQL server in the list, select it and click Uninstall/Change:

  3. Click Repair in the window that appears:

  4. After repair install completes, retry the backup.

If the issue is not resolved, troubleshoot snapshot issues on Hyper-V as described in Troubleshooting Hyper-V snapshot issues


If there is no SQL server on the virtual machine:

Troubleshoot VSS-related issues on the guest OS as described in KB 36200: VSS Troubleshooting Guide