Login broken after motherboard swap


Active Member
Apr 6, 2019
California, US
I can't seem to even attempt a login anymore after swapping motherboards.

Please note before you read further that the PHYSICAL console login (accessed over IPMI) is broken, not the Web GUI. I know swapping the motherboard rendered my old networking configuration completely wrong. I'm trying to get into the system and fix that networking configuration.

The issue is that I can get to the login prompt but once I enter "root" and hit enter, the login screen freezes for a few seconds and then resets as if nothing happened. Here's what it looks like:


Has anyone ever seen anything like this before? Any guesses at how I might recover here? I can reinstall Proxmox from scratch if it's not salvageable, it's not the end of the world.
I edited /etc/network/interfaces at the recovery console and after an `ifreload -a` I confirmed with `ip l` and `ip a` that things looked good. When I reboot I still can't login from the normal login prompt (same reset issue in first post) and I can't access the web GUI.

Oh, I didn't see this before, but there's a lot of console errors at the login prompt before it resets the first time:

Setting `intel_iommu=off` allowed me to boot and login without error! I was able to do that by editing the grub entry for Proxmox at the boot screen (press 'e') and changing `intel_iommu=on` to `intel_iommu=off`, before pressing F10.

Unsurprisingly, I was wrong, and the VM was set to boot automatically. Now it failed to boot (because of iommu being disabled), which is why I can use Proxmox again.

Further recovery steps:
  • Logged-in to Proxmox
  • Removed the PCI devices from the VM
  • Set the VM to not start at boot
  • Re-enabled intel_iommu in /etc/default/grub, `update-grub`
  • `reboot`
  • Logged-in to Proxmox
  • Confirmed iommu is back on with `dmesg | grep -e DMAR -e IOMMU` and confirming "DMAR: IOMMU enabled" output
  • Added the correct PCI devices to VM
  • Booted VM up, confirmed it can start without issue.
  • Set it back to auto-start on boot. Rebooted Proxmox with the VM, just to triple check all is well and both Proxmox and the VM come up cleanly.
  • Like
Reactions: Falk R.


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