31347: Acronis Cyber Protect: Application-aware backup fails with "Failed to get the metadata from the 'VMware Snapshot Provider' extension library" or "VSS metadata is missing or corrupt"

Last update: 24-08-2021


Application-aware backup fails with one of these errors:

Error 1

Error code: 34865165
Fields: {"$module":"aavb_backup_command_addon_vsa64_23140"}
Message: Failed to get the metadata from the 'VMware Snapshot Provider' extension library.
Error code: 65520
Fields: {"$module":"aavb_backup_command_addon_vsa64_23140","code":2147942402}
Message: The system cannot find the file specified

See solution 6.

Error 2

Exchange-aware backup fails with:

Error code: 358
Module: 149
LineInfo: 4db9605401c1509b
Message: VSS metadata is missing or corrupt.
Error code: 1001
Module: 460
LineInfo: df98e120ab10cc45
Message: Failed to parse MsExchange VSS writer metadata.
Error code: 1003
Module: 460
LineInfo: df98e120ab10cc2d
Message: Expected XML tag not found: WRITER_COMPONENTS

Error 3

Error code: 367
Module: 149
LineInfo: 63216460909351a3
Fields: command : --check-env
Message: The agent on the guest system has failed to process the request.
Error code: 1
Module: 470
LineInfo: dd1e7a681d3fe6a8
Fields: $module : C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\1995738C-A9A9-4B1F-ADBE-5C7E2D8A98EE\exchange_backup_agent.exe
Message: Failed to process command 'CheckEnvironment'.
Error code: 25
Module: 470
LineInfo: 43403141c47105d9
Message: The VSS components of VMware Tools are corrupted or not installed.

See Solution #3 for this specific error. Note the line in bold:


There are several possible causes. Please look through the Solution section of the article.


  1. If you are running Microsoft Exchange on Windows 2008-based machine in ESX(i) 4.1 or higher environment then please ensure that disk.EnableUUID parameter is present in the Exchange VM configuration. For detailed instructions please see VMware KB:  Enabling Windows 2008 application-consistent quiescing on ESX/ESXi 4.1.
  2. Exchange-aware backup is not possible if Microsoft Exchange is installed on Windows 2003 SBS edition without additional adjustments. By default, the Setup program for Microsoft Windows Small Business Server 2003 turns off the Microsoft Exchange Server 2003 writer for the Volume Shadow Copy service. To protect data using Acronis vmProtect 7, the Exchange 2003 writer must be turned on: See Microsoft TechNet: Troubleshooting Exchange Server Protection Issues. For Exchange 2007/2010 versions the VSS writer is turned on by default, so these versions are not affected by this issue. This is a by-design behavior.
  3. This solution applies to ESX(i) 5.0 and older. This solution applies only if you have the The VSS components of VMware Tools are corrupted or not installed error message.

    The VMware Snapshot Provider service is required for proper application level quiescing. The solution is to register the necessary COM component manually as described in VMware KB: Unable to create snapshots on Windows guest operating systems. To ensure the proper registration of VMware Snapshot Provider COM component use the following command for registration which sends the log output into a file: "C:\Program Files\VMware\VMware Tools\COMREG.EXE" -register "C:\Program Files\VMware\VMware Tools\Drivers\vss\VCBSnapshotProvider.dll" "VMware Snapshot Provider" "vmvss" "VMware Snapshot Provider" > C:\register.log 2>&1 . The successful log will look similar to the following:

    Couldn't find application to unregister: VMware Snapshot Provider
    Creating new COM+ application (VMware Snapshot Provider)...
    Setting application options...
    Creating the service...
    Registering the DLL...
    Securing the application...
    Searching for admin group using WMI...
    Searching for LocalSystem account using WMI...
    Granting new role to LocalSystem user...

  4. In case the VMware tools were installed on the Exchange VM in non-interactive (silent) mode the VSS modules may not be registered properly. The solution in this case would be to re-install VMware tools in interactive mode by logging into VM and performing the installation of the VMware tools.
  5. In case there is User Account Control enabled inside the VM running Microsoft Exchange, make sure you have installed the Exchange Backup Agent  prior to running Exchange-aware backup of this VM. It can be extracted from Acronis Backup for VMware (former vmProtect) installation package: look for "Acronis Backup for VMware Backup Agent" component.
  6. If nothing of the above helps then the most probable reason is incorrect vss_manifests***.zip archive generated while quiescing the Exchange VM, i.e. it is not generating proper VSS manifest output. Please ensure that your VM meets all prerequisites imposed by VMware for Application-consistent quiescing which depend on vSphere version and the Guest OS type. For example Windows 2008 installed on IDE disks in vSphere 4.1+ environment doesn't support Application-consistent quiescing. Application-consistent quiescing is required to get non-empty VSS manifests .zip output: See the following description of VSS handling specifics from VMware

    When creating a quiesced snapshot of the VM from vSphere Client interface there must be vss_manifests***.zip file generated on the datastore in the folder where this VM is:

    Under normal circumstances, the VSS manifests .zip file is not empty, however if there are some problems with the VMware tools then the outputs may be corrupted even though the VM meets the requirements for Application-consistent quiescing.
    Reinstall VMware tools.

  7. If vss_manifests***.zip archive is not created on the datastore, check tools.conf (see Configuration File Location). VSSenabled parameter must be set to True. If VSSenabled=false, change the value to true and restart VMware tools services.

  8. If re-installation of VMware tools or other suggestions above does not help then please collect the following information after creation of the quiesced snapshot of the Exchange VM and contact Acronis Support with the following diagnostic information:


    • Outputs of the vssadmin list writers command from the guest OS (Exchange VM) in to check that there are no failing VSS writers. See VSS Log Files;
    • Windows System Information from the guest OS (Exchange VM): Start -> Run -> msinfo32 -> Save to File…
    • Windows Event Logs from the guest OS (Exchange VM): Start -> Run -> eventvwr.msc. Both System and Application logs are required.
    • The vss_manifests***.zip file obtained in step 6 of the above described steps.

More information

See also Acronis Backup for VMware 9.