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VM backup fails with the error code VMOMI1 on a virtual machine running on Windows Server 2019

 

Problem description

When backing up a virtual machine running on Windows Server 2019, a failure to quiesce the VM occurs. The following error is generated: 

VMOMI1: An error occurred while saving the snapshot: Failed to quiesce the virtual machine.

Cause

The VM backup fails because Windows Server 2019 is unable to identify the recovery volume that is included in the VSS SnapshotSet during the VSS process. The Application Event logs on the guest OS show the following event:

Log Name: Application

Source: VSS

Event ID: 12363

Description:

An expected hidden volume arrival did not complete because this LUN was not detected.

Operation:

Exposing Volumes

Locating shadow-copy LUNs

PostSnapshot Event

Executing Asynchronous Operation

Context:

Execution Context: Provider

Provider Name: VMware Snapshot Provider

Provider Version: 1.0.0

Provider ID: {564d7761-7265-2056-5353-2050726f7669}

Current State: DoSnapshotSet

Resolution

As per VMware, this issue is resolved in Windows Server version 1809 and all versions of Windows Server 2019 OS Build 17763.1012. For more information, see January 23, 2020—KB4534321 (OS Build 17763.1012). This issue can be fixed as follows:

  • Use the BIOS boot and MBR disks since Windows Server 2019 installation
    For Extensible Firmware Interface (EFI) systems, Microsoft requires Windows installed on the GPT disks. This issue can be resolved by using an MBR disk layout instead of GPT while provisioning the machines.

    Note: MBR can be used if the disk is <= 2TB. If a machine already has GPT, backup all the data from the disk, and convert the disk to MBR. For more information about how to convert a GPT disk into an MBR disk, refer to the Microsoft article.

  • Fall back to the filesystem-consistent snapshot
    1. Navigate to %SystemDrive%\ProgramData\VMware\VMware tools.
    2. Create or edit the Tools.conf file with a text editor.
    3. Add this entry (Or modify existing entry as required).
      [vmbackup]
      vss.disableAppQuiescing = true
    4. Save the file.

Refer to this VMware KB for the latest updates regarding this issue.