Upgrade 1.3.4 to 1.4.0-epa3 - interface IPs missing

I have done an update of a test installation of a vyos running inside a vm on a proxmox server. The System was on 1.3.4 and did nothing special only. Have a static IP on lan, a wan via dhcp and then nat the internal network to the outside network.

The following commands where issued:

vyos@vyos1.sh.local:~$ show version

Version:          VyOS 1.3.4
Release train:    equuleus

Built by:         Sentrium S.L.
Built on:         Fri 13 Oct 2023 12:10 UTC
Build UUID:       0b20543f-d1b6-49e5-b36b-95a069c63788
Build commit ID:  986c77ac08c552

Architecture:     x86_64
Boot via:         installed image
System type:      KVM guest

Hardware vendor:  QEMU
Hardware model:   Standard PC (i440FX + PIIX, 1996)
Hardware S/N:
Hardware UUID:    a8642992-8049-4365-8a32-e973353cb1b8

Copyright:        VyOS maintainers and contributors
vyos@vyos1.sh.local:~$ add system image https://cdn.vyos.io/1.4.0-epa3/generic-iso/<id>/vyos-1.4.0-epa3-amd64.iso

Checking SHA256 checksums of files on the ISO image... OK.
What would you like to name this image? [1.4.0-epa3]:
OK.  This image will be named: 1.4.0-epa3
Installing "1.4.0-epa3" image.
Copying new release files...
Would you like to save the current configuration
directory and config file? (Yes/No) [Yes]:
Copying current configuration...
Would you like to save the SSH host keys from your
current configuration? (Yes/No) [Yes]:
Copying SSH keys...
Running post-install script...
Setting up grub configuration...

vyos@vyos1.sh.local:~$ reboot

After the reboot I was not able to ssh in it.
When I did a show interfaces on the console of the vm, both interface eth0 and eth1 didn’t have an IP. Also show configuration didn’t show and interface config. Everything else seems to bet there. (NAT, Firewalls…). I have a save of the converted config.

A reboot to the 1.3.4 version worked fine and everything is up again.

Please try to update in this order: 1.3.4 -> 1.3.7 -> 1.4.0-EPA3.

When you are jumping to the new major release it is better to do this from the most fresh previous version release.

Also, if you can share the config.boot file from 1.3.4 and 1.3.7, before the update, that would help to understand the nature of the problem.