Diagnose Hyper-V by separating host health, VM state, virtual-disk chains, networking, replication and cluster dependencies.
- For a VM that will not start, record the exact VMMS or Worker event and check the VM configuration and its VHDX/AVHDX chain.
- For checkpoint, backup or merge problems, check free space and the backup job before changing disks.
- For migration or replication, compare host compatibility, network reachability, authentication and destination storage.
Command examples
Adapt placeholders, permissions and target systems before using an example. These examples are documentation; no command runs from this page.
Get-ComputerInfo | Select WindowsProductName,WindowsVersion,OsBuildNumberGet-WinEvent -LogName 'Microsoft-Windows-Hyper-V-VMMS-Admin' -MaxEvents 50Get-WinEvent -LogName 'Microsoft-Windows-FailoverClustering/Operational' -MaxEvents 50Read Hyper-V events
Use the VMMS, Worker and FailoverClustering logs for the affected operation. Correlate their timestamps with System, storage and backup events.
Check Hyper-V connectivity
Confirm the source and destination names, configured migration networks and service ports. A reachable TCP port alone does not prove that authentication or migration will succeed.
Collect the starting state
Record host version, VM state, virtual switches, disk paths, replication state and cluster health where applicable. Compare results before and after a targeted change.
Check virtual disks first
For startup failures, verify that storage and every required VHDX/AVHDX parent are available before changing the VM configuration.
AVHDX is part of a disk chain
An active AVHDX file is not a disposable temporary file. Use the supported checkpoint or consolidation workflow.
CSV capacity and free space
Checkpoint merges and backups can require additional temporary capacity. Check the CSV or datastore beneath the guest volume.
Migration: network and authentication
Check the configured authentication method and host compatibility. On Windows Server 2025, Credential Guard affects CredSSP-based migration; Microsoft documents Kerberos delegation as the compatible approach.
Use the relevant logs
VMMS, Worker and FailoverClustering events provide operation-specific evidence that the System log alone may miss.
Establish cluster health
Check nodes, networks, CSV access and quorum before attempting to move or force a clustered role.