Unable to take quiesced snapshot of Windows Server virtual machine with GPT disk without MSR partition

Products

• VMware vSphere ESXi
• VMware vCenter Server

Issue/Introduction

Quiesced snapshots or backups fail on Windows Server virtual machines with the error VssSyncStart operation failed: IDispatch error #8454 (0x80042306). This issue is caused by a configuration mismatch between the virtual disk layout and the Microsoft Volume Shadow Copy Service (VSS) framework.

Environment

• VMware vSphere ESXi 6.5
• VMware vSphere ESXi 6.7
• VMware vSphere ESXi 7.0
• VMware vSphere ESXi 8.0
• VMware vCenter Server.
• Windows Server virtual machines using GPT disks.

Cause

The virtual machine contains a GPT disk missing the Microsoft Reserved (MSR) partition. VMware Snapshot Provider operates under the Microsoft VSS framework, which requires an MSR partition on all GPT disks to execute IOCTL_DISK_SET_SNAPSHOT_INFO commands. The absence of this partition causes the VSS process to fail.

Resolution

 Identify the impacted disk by executing the following in an administrative command prompt on the affected Virtual Machine:

diskpart
list disk
select disk #
list part

If the partition table shows an MSR partition is missing, use one of the following options:

• Option 1: Add a new GPT disk containing an MSR partition, migrate the data to the new disk, and remove the original GPT disk.
• Option 2: If insufficient space exists to create a new MSR, shrink the volume by the default MSR size (32MB or 128MB) to accommodate the partition.

Workarounds If snapshots remain necessary without application-consistent backups, utilize these alternatives:

1. Disable VMware Snapshot Provider: Disable or uninstall the component from VMware Tools.
2. Disable Guest Quiescing: Configure the snapshot or backup job to avoid quiescing the guest OS.
3. Modify Backup Configuration: Disable the pre-backup quiesce call to the vSphere environment (consult backup vendor documentation).

Note: Disabling guest quiescing prohibits application-consistent backups.

Additional Information

• To speak with a customer representative or a Support Engineer, see Contact Support. Select the respective region at the bottom of the page.
• Windows and GPT FAQ (Microsoft Documentation).