Avamar: Hyper-V backups fail with VSS_E_OBJECT_ALREADY_EXISTS

Summary: Avamar: Hyper-V backups fail with VSS_E_OBJECT_ALREADY_EXISTS

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Symptoms

Hyper-V backups fail with the following errors:

2016/02/26-05:32:20.10400 [hypervvss_assist]  
ERROR: COM call m_pVssObject->AddToSnapshotSet((LPWSTR)*(volume.to_uwstring()),
vss_provider_guids[j], &SnapshotID) failed.
2016/02/26-05:32:20.10400 [hypervvss_assist]  - Returned HRESULT = 0x8004230d
2016/02/26-05:32:20.10400 [hypervvss_assist]  - Error text:
VSS_E_OBJECT_ALREADY_EXISTS
2016-02-25 21:32:20 avhypervvss Error <13846>: Unable to expand backup targets
...
2016-02-25 21:32:20 avhypervvss Error <12986>: Could not expand targets
correctly.
...
2016-02-25 21:32:20 avhypervvss Error <0000>: Backup did not complete
successfully.

Cause

1.  Multiple mount points pointing to the same hard drive volume. VSS plug-in builds up a list of affected volumes that need to be in the snapshot. If two different paths pointing to the same volume are included in this list, the backup will result in a VSS error and a failed backup.

2.  Possible code bug in Avamar v7.0 of the Hyper-V VSS plug-in.

Resolution

Perform the below steps:
  1. Remove the redundant mount point.  
  2. Upgrade to a newer version of the Hyper-V VSS plug-in. The latest version available is 7.2.101-32.

Affected Products

Avamar

Products

Avamar
Article Properties
Article Number: 000064119
Article Type: Solution
Last Modified: 05 Mar 2025
Version:  4
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