Azure Site Recovery: Test Failover Issue — Managed Disk Creation Failure

BrianWong-8919 0 Reputation points
2026-10-18T20:46:36.92+00:00

Problem description

I am attempting to perform a test failover for a zonal Azure virtual machine using Azure Site Recovery, but the operation fails during managed disk creation. The error reported is: "Source is not a valid VHDX file." I need assistance in understanding and resolving this issue.

Environment

Azure Site Recovery, Azure cloud, Azure virtual machine, zonal VM, region not specified in the case information.

What I've already tried

I have reviewed the initial failure report and checked the Azure portal for any residual test resources or previous failures. I verified that no earlier test failover or cleanup jobs have left residual resources. I also checked the self-help documentation for Azure Site Recovery, but it did not provide a specific solution for this error message.

Current status

The latest status indicates that the test failover failed during managed disk creation with a "CloudStorageUnexpectedError" and the message "Source is not a valid VHDX file." I am seeking guidance on how to troubleshoot and resolve this disk resource provider error to successfully complete the test failover.

Azure Site Recovery
Azure Site Recovery

An Azure native disaster recovery service. Previously known as Microsoft Azure Hyper-V Recovery Manager.

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  1. kagiyama yutaka 5,655 Reputation points
    2026-10-18T23:20:24.03+00:00

    I think the VHDX error alone isn't enough to say the source disk is corrupt. Get the full error from the failed task in Site Recovery jobs, then check the target subscription's Activity Log for a matching Microsoft.Compute/disks/write failure.

    For a single VM test failover outside a recovery plan, Custom lets u try a different recovery point. If that fails too, send Azure Support the job IDs, full errors, UTC timestamps, recovery-point timestamps, target region and zone settings, and any matching Activity Log correlation ID.

    Additional info:

    https://learn.microsoft.com/en-us/azure/azure-portal/supportability/how-to-create-azure-support-request

    　　　←Azure support request

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