This topic describes common workarounds of issues that you might encounter while backing up or restoring Hyper-V virtual machines.

If the disk sequence changes after restore, the boot order changes for the Linux virtual machine and the virtual machine boots into maintenance mode or some virtual disks are not visible.

For the Linux virtual machine, change the disk sequence in /etc/fstab. The virtual machine boots without any problem after you enter the correct disk sequence. For more information, see RedHat documentation. [External link]

When VM is restored on another host, sometimes it fails to start with an error: ' Unnamed VM' could not initialize. (Virtual machine ID).
The event log shows the error: The security ID structure is invalid (0x80070539).

On the Hyper-V host:

For more information, see Virtual machine cannot start - The security ID structure is invalid (0x80070539)[External link to a Microsoft support article.]

One of the reasons why a virtual machine FLR fails is the presence of user recovery points. If user recovery points are present, Druva backs up a virtual machine, however, FLR from such virtual machine backups is currently not supported. The backup job for such a virtual machine is marked as successful with errors.

Delete the user recovery points and backup the virtual machine to use file-level restore.

This error can occur if you are restoring a virtual machine or a virtual disk to a Windows Server 2008 or Windows Server 2008 R2 host with SMB share target, and appropriate write issues on the share are not available.

To resolve this issue:

For example:

To flush and purge the existing authentication tickets:

Run the following commands as administrator on the Hyper-V host:

Create a new folder and apply write permissions to the target folder

Run the following commands as administrator on the Hyper-V host

📝 Note
​Use the above example as a guide. Replace the inputs SomeFolder, hypervhost1, and smbsharesystem based on your setup.

This issue can occur when you are restoring virtual machines to Windows 2008 server, and you have multiple virtual disks of different types attached to it, such as simple, spanned, striped, or mirror disk.

In such a case, after you restore the virtual machine and turn it on, you can only see the primary disks in the virtual machine.

Launch the DISKPART utility or the disk management console ( diskmgmt.msc ), select each disk individually, and bring each virtual disk online manually. For example, run the following commands in the DISKPART utility:

This issue can occur when you generate a re-registration activation token for one host and use the token to re-register another host. For example, you have two hosts registered with Druva for backup, hosts h1 and h2. Host h1 has virtual machines a1, a2, and a3 running on it, and host h2 has virtual machines b1 and b2 running on it.

If you generate a re-registration token for the host h2, but install and activate the agent using the re-registration token on host h1:

In this example, there are two hosts that are listed as h2, however, the host that is still connected to the Druva Cloud is host h1. To resolve this issue, re-register the host h1 that is listed as host h2 with a new re-registration token. After you re-register the host, you can see that the host h1 is now listed correctly on the Management Console. After you re-register the host h1, select the disconnected host h2 and re-register it with a new re-registration token. After you re-register the host h2 with the correct activation token:

The creation of the production checkpoint on Hyper-V Guest OS Windows Server 2012 fails for the older version of Integration Services. For older version of Integration Services, the Progress logs shows the following details:

To ensure that your backups are application-consistent, download and install updates on the Windows update page of the Hyper-V host.