Proxmox Version 9 Linux VM Backup / Restore fail

[homerjs]

After upgrade from PVE 8 to 9 , only VMs with Linux (Ubuntu) fail to Backup and fail to Restore.
VM with WIndows is working good.
Backup Log : 06.08.2025 20:42:11 :: ALVAULT01 : Failed to perform backup: Failed to map disks
???

[homerjs]

Workaraound:
Liunx VM , change Hardware > Machine from Default(i440fx) to I440fx Version 9.2
it works

[Mildur]

Hi Homer,

Welcome to our forum.

Please note that for future posts about technical issues, this is not a support forum, as explained in the forum rules displayed when you click New Topic. If you encounter a technical problem, please contact our customer support team first.

Regarding your issue, I'm glad you found a solution. However, I’d like to point out that Proxmox v9 was released only a few days ago. Our general goal is to provide official support for a new version within 90 days after GA. We cannot guarantee at this time that Proxmox 9 is fully compatible with the current build of Veeam Backup & Replication.

For future Proxmox major updates (10, 11, 12, ...), I recommend waiting until we explicitly mention support for the new version in our Help Center. Otherwise, you may risk being without backups for weeks or even months, unless you redeploy a previously supported Proxmox version.

Best regards,
Fabian

[Gostev]

Simply put, Proxmox v9 if not yet supported. To the point where we can't guarantee that "successful" backups following your fix are actually recoverable. Adding this just to be sure future readers don't read the workaround posted by homerjs as the magic solution that enables Proxmox 9 support.