Proxmox Backup Server WebGUI Network Interfaces "unknown iface option auto (400)"

stonebream

New Member
May 4, 2025
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I have run into an error message in the webGUI that says line 10: unknown iface option auto (400). The IP configuration seems to be working as I get IPv6 as expected but this error still shows and prevents me from using this section of the webGUI. I use this auto option on PVE with no such error showing.

Here is my /etc/network/interfaces
Code:
auto lo
iface lo inet loopback

auto nic0
iface nic0 inet static
        address 10.0.10.75/24
        gateway 10.0.10.1
# Main Interface

iface nic0 inet6 auto
        accept_ra 2
        autoconf 1

source /etc/network/interfaces.d/*

Here is a screenshot of the error:
1771206502141.png

Package Versions:
proxmox-backup: 4.0.0 (running kernel: 6.17.9-1-pve)
proxmox-backup-server: 4.1.2-1 (running version: 4.1.2)
proxmox-kernel-helper: 9.0.4
proxmox-kernel-6.17.9-1-pve-signed: 6.17.9-1
proxmox-kernel-6.17: 6.17.9-1
proxmox-kernel-6.17.2-1-pve-signed: 6.17.2-1
ifupdown2: 3.3.0-1+pmx12
libjs-extjs: 7.0.0-5
proxmox-backup-docs: 4.1.2-1
proxmox-backup-client: 4.1.2-1
proxmox-mail-forward: 1.0.2
proxmox-mini-journalreader: 1.6
proxmox-offline-mirror-helper: 0.7.3
proxmox-widget-toolkit: 5.1.5
pve-xtermjs: 5.5.0-3
smartmontools: 7.4-pve1
zfsutils-linux: 2.4.0-pve1