[SOLVED] No more network adapter after pbs 4 upgrade

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neoraptor

New Member
Jan 14, 2025
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Hello,
I upgraded my whole homelab today to PVE 9 and PBS 4.
All went well for PVE, but I lost network connectivity on my PBS instance.

Hardware is a Dell Wyse 5070 and I have this in the logs:
1754482065814.png
1754482809720.png

System worked without issues before upgrading.
How can I further troubleshoot and fix this issue?

Thanks for your suggestions,
 
Last edited:
Hi,

can you first of provide the output of proxmox-backup-manager versions --verbose, just to be sure?
Also, the (full) output of tail -n+1 /etc/network/interfaces /etc/network/interfaces.d/* and ifreload -avd would be helpful, maybe that gives some more information.
 
neoraptor said:
Hmm, it looks like the upgrade to version 4 didn't worked. I did follow the migration guide
Click to expand...
Yeah, the correct version for PBS 4.0 for the ifupdown2 package (currently) is 3.3.0-1+pmx9.
So that's probably why it errors out, some incompatibility I'd guess.

Anyway, can you show your configured apt repositories? tail -n+1 /etc/apt/sources.list; tail -n+1 /etc/apt/sources.list.d/*
And what does apt update && apt list --upgradable report?
 
Here is the apt repos config:
1754484826587.png

As I don't have a NIC online (I am connected through a IP KVM), I can't perform the apt commands.
 
neoraptor said:
As I don't have a NIC online (I am connected through a IP KVM), I can't perform the apt commands.
Click to expand...
You can add an (static) IP manually to the interface using:

Code: 
ip address add <ip>/<mask> dev enp1s0
ip route add default via <gateway-ip> dev enp1s0

That should restore networking until the next reboot (or ifreload invocation).
 
Did you use apt full-upgrade as recommended? Or apt upgrade? As the latter is known to cause breakages.

Anyway, just run apt full-upgrade, that should fix that problem.
 
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Reactions: neoraptor and Chris
thx for this help, I had a similar issue but in addition my network interface shown using ip a was down. After using your how to I figured out that instead of ifupdown2 I had still the installation if ifupdown. So I used a lot of your fixes and something in addition I want to share.

How I recognized this: Using proxmox-backup-manager versions --verbose showed the version of ifupdown as UNKNOWN.

step by step if you have the issue i have (interface is called enp0s18 for me):
- my interface seemed to be down (ip a) so set it up: ip link set enp0s18 up
- set fixed ip again (not sure if needed): ip address add <ip>/<mask> dev enp0s18
- set route to have internet again: ip route add default via <gateway-ip> dev enp0s18
- install ifupdown2 - it suggest to uninstall old ifupdown which is fine (needed to do it twice): apt install ifupdown2

Reboot and your host should be up and available again
 
Last edited:
WolfTongue said:
thx for this help, I had a similar issue but in addition my network interface shown using ip a was down. After using your how to I figured out that instead of ifupdown2 I had still the installation if ifupdown. So I used a lot of your fixes and something in addition I want to share.

How I recognized this: Using proxmox-backup-manager versions --verbose showed the version of ifupdown as UNKNOWN.

step by step if you have the issue i have (interface is called enp0s18 for me):
- my interface seemed to be down (ip a) so set it up: ip link set enp0s18 up
- set fixed ip again (not sure if needed): ip address add <ip>/<mask> dev enp0s18
- set route to have internet again: ip route add default via <gateway-ip> dev enp0s18
- install ifupdown2 - it suggest to uninstall old ifupdown which is fine (needed to do it twice): apt install ifupdown2

Reboot and your host should be up and available again
Click to expand...
I had to set the ip addr on my interface first, then bring it up, but was able to then do "dpkg --configure -a" because "apt dist-upgrade" didn't finish overnight but I lost access to the console and then had to kill apt.. had to do the same for my 3 proxmox installs, but didn't lose network on them.
 
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