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.