Possible bug, case #06028279

[Han]

I think I have discovered a bug in VBR12.

Running the NFR version of VBR12 12.0.0.1420 P20230412 on a Windows Server 2022 OS in a workgroup.
Running VCSA 7.0.3 build 21477706
Running ESXi 7.0.3 build 21424296

Guest files restore of VM's running Windows Server 2019 succeed.
Guest files restore of VM's running Windows Server 2022 fail with the following error in the Backup Browser:

Failed to call RPC function 'RegAttachHiveFile': The system has attempted to load or restore a file into the registry, but the specified file is not in a registry file format. Failed to call RegLoadKey function.

Followed by the following error:

Failed to mount backup.

[PetrM]

Hello and Welcome to Veeam R&D Forums!

Let's wait for the conclusion from our support engineers. If it's a bug and not an infrastructural issue, we'll try to find some options to fix it at the level of our code.

Thanks!

[Han]

Unfortunatly support has closed that case. I guess since I am using an NFR edition of VBR12 (in my lab).

[PetrM]

Hello,

As stated in our support policy:

Free license customers have support via web or email only on a best effort basis only.

You may try once again, every single attempt to open a case increases your chances to get support.

Thanks!

[ArturE]

Hello,

We encountered this issue during our tests while using the same Windows version, and it turned out that the configuration registry database on the source machine was corrupted before/during the backup.

Have a look through this Microsoft thread and see if it helps. The log Svc.VeeamInstallerDll.log file on the backup server will contain the name of the problematic registry: Failed to complete RPC request. Method: [RegAttachHiveFile] followed by the registry. To note:

- the corrupted registry needs to be checked on the source machine, not on the backup server (but it's probably a good idea to check on both machines)
- after the corruption is repaired, start a new backup chain

If that doesn't solve the issue, there is a workaround: launch a Linux guest file restore wizard, and on the Helper Host select to use a temporary helper appliance (or a Linux machine with NTFS support, if it's available). This will allow you to browse the contents of the backup, which you can then restore using the Copy To functionality (instead of Restore/Restore to)

Best regards,
Artur

[ArturE]

For anyone encountering this specific error, below you can find the way to solve it:

Errors in logs:
Failed to complete RPC request. Method: [RegAttachHiveFile]
Failed to call RPC function 'RegAttachHiveFile': The system has attempted to load or restore a file into the registry, but the specified file is not in a registry file format. Failed to call RegLoadKey function.
Loading registry key: KeyPath: [SYSTEM<uuid>], File: [C:\Windows\TEMP\SYSTEM<uuid>] Failed.

1. The registry corruption was treated on most VMs using the steps from the Microsoft thread linked above
dism /online /cleanup-image /restorehealth /source:<specify a source if applicable> /limitaccess
sfc /scannow

If this step doesn't fix the issue entirely, see step 2.

2. There is a User registry hive file, and it stores per-user CLASS information. It is represented at HKEY_CURRENT_USER\Software\Classes. Renaming this file & rebooting the machine will force the file to be recreated. There is a caveat: this UsrClass.dat file is usually locked down by the system processes and you can't easily access or modify it with the currently logged in user.

Navigate to %localappdata%\Microsoft\Windows
In it, you will find a file called UsrClass.dat (it is a hidden file)
Rename it to UsrClass.dat.bak (it must be renamed for all user profiles)
Reboot the machine
Create a new backup of this machine
Launch the Guest OS File Restore from this latest backup

[PetrM]

Hello,

For all future readers: please always contact our support team in case of a technical issue and don't hesitate to ask your engineer to make sure that your problem 100 % matches the description from the post above and that the solution can be safely applied. Our possibility to analyze technical issues via the forum posts is very limited, we won't be able to assist you if something goes wrong.

Thanks!