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.

[gergo.kerekes]

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

Confirmed! It works!

Thank you!

[NuAngel]

I saw another thread talking about restore failures, and how switching the machine type to i440fx 9.2 solved their issue, but I've had no such luck.

I also understand that there may not be full support for ProxMox 9.x for at least 90 days as it is still a relatively "hot off the presses" release. But I'm hoping that in the intervening 40-ish days since the other thread was started, someone might have some advice for me, so I wanted to created this post!

Upon deployment, the Proxmox worker / Proxy device is created by Veeam and boots up / updates just fine (although I did note a bug with that assigning the wrong number of cores/threads {should I make that its own thread?}). However, when I try to run a backup, all of my VMs, whether they are Windows or Linux guests, all report "Failed to perform backup: Failed to map disks."
[*]It then says "Backing up the VM xxx in the 'HotAdd' mode'
[*]Then reports that the worker was shutdown successfully.

No backup is created. These VMs are stored on a ZFS3 pool, is the difficulty Veeam being able to read ZFS?

I will note: the machine type created by this version of Veeam / Proxmox is a q35 machine, not an i440fx. Changing the machine type to i440fx, even changing the version to 9.2, or 9.2+pve1 and or changing the BIOS to SeaBIOS from OVMF (UEFI), etc... no changes to the 'hardware' of the VeeamWorker in Proxmox seemed to (if anything the backup didn't even get as far).

Sorry for a bit of word-vomit, but I'm open to any tips or suggestions?