My experience with elevate-cpanel and ubuntu 22.04 to 24.04

I successfully used elevate-cpanel to upgrade a Xen VM from ubuntu 22.04 to 24.04 and I hit quite a few snags. I wanted to document what I ran into, and how I fixed it, so anyone else might also benefit.

Problem 1: KernelCare blocker. When I ran elevate-cpanel --check, I would get this error:
[ERROR] *** Elevation Blocker detected: ***
   ELevate does not currently support KernelCare for upgrades of Ubuntu.
   Support for KernelCare on Ubuntu will be added in a future version of ELevate.

I don't have a KernelCare subscription, so I ran: sudo apt purge kernelcare. That got rid of kernelcare and passed that blocker. Obviously someone who cares about kernelcare and has a subscription should probably not do this.

Problem 2: apt sources

   The following unsupported list files were found in /etc/apt/sources.list.d:
   imunify-rollout-bypass.list
   labs-consol-stable.list
   alt-common-els-rollout.list

That's easy enough. Just follow instructions and rename them to names like alt-common-els-rollout.list.disabled. After doing that, I could run /scripts/elevate-cpanel --start and it started.

Problem 3: No IP address. Starting with phase 3 of the elevate process, my system would not get its IP address from DHCP when it booted. I tracked this down to device renaming. It appears that under 22.04, my ethernet device was eth0, and under 24.04 it's enX0. At first, I was in a bit of a panic, so I would just login on the console and run `sudo dhcpcd` and it would get an IP so that I could continue the upgrade, but that's not obviously not surviving reboots.

Problem 4: No DNS resolution. Even after manually launching dhcpcd to get an IP address, I couldn't continue elevate-cpanel because DNS resolution was broken. My /etc/resolv.conf was broken by upgrading to 24.04, and that seems to be a somewhat common issue with these ubuntu upgrades. This ArchWiki article explains what to do to fix it. It involves removing the symbolic link at /etc/resolv.conf, rewriting it, and making sure systemd-resolved is enabled and running.

I did both the DHCP and DNS steps manually a few times just so the elevate-cpanel process could complete. Once the upgrade was complete, I fixed the network interface naming problem.

In my case, the file /etc/cloud/cloud.cfg.d/90-installer-network.cfg on my system looked like this:
   network:
     version: 2
     ethernets:
       eth0:
         dhcp4: true

I changed it to:
   network:
     version: 2
     ethernets:
       enX0:
         dhcp4: true

After a reboot, it worked fine.

This was a lot rockier than I expected. That was a LOT of rebooting. I did get there in the end. I hope I save someone else a bit of heartburn.