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Druva Documentation

Troubleshooting VM backup failure in Phoenix with VMWARE_VMOMI1

This article applies to:

  • Environment: VMware
  • Product edition: Phoenix

Problem description

Phoenix VM Backup failed with VMWARE_VMOMI1  "An error occurred while saving the snapshot: Failed to quiesce the virtual machine"

Phoenix VM Backup fails with VMWare_VMOMI1 error: "An error occurred while saving the snapshot: Failed to quiesce the virtual machine".

What is Quiescing?

Quiescing a file system is a process of bringing the on-disk data of a physical or virtual computer into a state suitable for backups. This process might include such operations as flushing dirty buffers from the operating system's in-memory cache to disk, or other higher-level application-specific tasks.

Quiescing indicates pausing or altering the state of running processes on a computer, particularly those that might modify information stored on disk during a backup, to guarantee a consistent and usable backup. Quiescing is not necessary for memory snapshots; it is used primarily for backups. [Source: Understanding VM snapshots in ESXi/ESX (1015180)]


The following error is found in the Phoenix Job logs:

ERROR] SyncError: Problem in VM configuration. 
[2018-03-01 18:03:21,971] [ERROR] Error <class 'pyVmomi.VmomiSupport.vim.fault.GenericVmConfigFault'>:(vim.fault.GenericVmConfigFault) { 
dynamicType = <unset>, 
dynamicProperty = (vmodl.DynamicProperty) [], 
msg = 'An error occurred while saving the snapshot: Failed to quiesce the virtual machine.',


Verify the issue on target VM

Verify whether the issue exists on the target VM as follows:

  1. Take a manual snapshot using vSphere Client or a web client.

  2. Right-click the VM and take a snapshot.

  3. Clear the Snapshot the virtual machine's memory checkbox and select Quiesce guest file system (needs VMware Tools installed) provided quiescing is enabled on the Phoenix virtual machine backup policy.
  4. Check the tasks and events for the VM if the snapshot was created successfully. 
    If the snapshots have failed, perform the steps mentioned the resolution below.


Consult the VMware team to fix the Quiesce error using the following KBs.

  1. VSS Issue
    1. Collect and review Windows event logs for VSS errors.
    2. Verify the state of VSS writers and providers by using the following commands. All writers must be stable and must have no error. 
      • vssadmin list writers
      • vssadmin list providers
    3. Check the VSS and other dependent servers.
    4. An issue with VSS in the guest VM
  2. VMware tools issue
    • Check whether the latest version of VMware tools is installed.
  3. Unable to create snapshots on Windows guest operating systems
  4. Cannot create a VMWARE_VMOMI1 snapshot because the snapshot operation exceeded the time limit for holding off I/O in the frozen virtual machine.