Login broken after motherboard swap

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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.

 

[altano]

I surprisingly can get into the recovery console (offered as a boot option).

 

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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:

 

[altano]

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.