Well, since I am after 6 hours of fighting with getting my production system working, first of all many thanks to the whole Proxmox team for screwing the upgrade process up and not informing users of it! I hope karma will thank you better than I can.
The story: 2 days ago I decided to upgrade my proxmox from 6.4 to 7.2. I have a test system, so went for upgrade there first. Followed the instructions and actually the upgrade process went with no problems. Problems occurred afterwards. First of all, the network stopped working. I have Dell R620 with 4 port network card and bridge. The ip link showed the eno1 eno2... correctly, all up, but vmbr0 down. Tried few things, did not find much in internet, however as the ip link started showing a comic altname by every link (enp1s0f0 etc), I replaced the eno1 names with these alternate names in /etc/network/interfaces and strangely enough (ip command still returned the old names) the network was back.
I shut the test system down and went to sleep.
The next day was the production system upgrade time. Backed up all vms, started the test system and copied the backups there (test system still working ok) and did the upgrade to the production system. Again, got no network afterwards, so wanted to do the exact steps, as the day before. To my surprise, after changing the names to enp1s0f0 in /etc/network/interfaces and restarting the service, the ip returned suddenly 42 interfaces (!!!!!!!!!!!!!). The network stopped working, and, strangely enough, also the test system network went down!!! Here just to mention, I use fast ip, so no dhcp could mess up. The next 4 hours (till midnight!!!, thank you proxmox guys!) I tried to get my prod system back to life. What is worth mentioning, with vmbr0 down and all other interfaces up, there was absolutely no error in the logs! The network started, status active, vmbr0 down.
At the end I decided to resign from bridge and have at least one working interface, so adjusted the settings and finally could start proxmox gui.
And here another surprise - the gui interface was actually then more helpful, than the shell, which for me happened the very first time in my entire linux carrier!!!
Gui showed the 4 eno interfaces, but also three enp1s0f0-type ones (so in total 7). Removing the enp1s0f0 and clinking on apply brought the solution, as a message stating "you need ifupdown2 in order to restart" ensured, that there was the old ifupdown still present and the upgrade process skipped this CRUCIAL installation.
After installing the ifupdown2, everything went back to normal on both systems.
So once again, thank you proxmox for your lousy work! Now get back to work and do it properly this time. Or at least inform people of that!
To all the others: do not perform upgrade unless you have physical or kvm access to the systems!!!!!
The story: 2 days ago I decided to upgrade my proxmox from 6.4 to 7.2. I have a test system, so went for upgrade there first. Followed the instructions and actually the upgrade process went with no problems. Problems occurred afterwards. First of all, the network stopped working. I have Dell R620 with 4 port network card and bridge. The ip link showed the eno1 eno2... correctly, all up, but vmbr0 down. Tried few things, did not find much in internet, however as the ip link started showing a comic altname by every link (enp1s0f0 etc), I replaced the eno1 names with these alternate names in /etc/network/interfaces and strangely enough (ip command still returned the old names) the network was back.
I shut the test system down and went to sleep.
The next day was the production system upgrade time. Backed up all vms, started the test system and copied the backups there (test system still working ok) and did the upgrade to the production system. Again, got no network afterwards, so wanted to do the exact steps, as the day before. To my surprise, after changing the names to enp1s0f0 in /etc/network/interfaces and restarting the service, the ip returned suddenly 42 interfaces (!!!!!!!!!!!!!). The network stopped working, and, strangely enough, also the test system network went down!!! Here just to mention, I use fast ip, so no dhcp could mess up. The next 4 hours (till midnight!!!, thank you proxmox guys!) I tried to get my prod system back to life. What is worth mentioning, with vmbr0 down and all other interfaces up, there was absolutely no error in the logs! The network started, status active, vmbr0 down.
At the end I decided to resign from bridge and have at least one working interface, so adjusted the settings and finally could start proxmox gui.
And here another surprise - the gui interface was actually then more helpful, than the shell, which for me happened the very first time in my entire linux carrier!!!
Gui showed the 4 eno interfaces, but also three enp1s0f0-type ones (so in total 7). Removing the enp1s0f0 and clinking on apply brought the solution, as a message stating "you need ifupdown2 in order to restart" ensured, that there was the old ifupdown still present and the upgrade process skipped this CRUCIAL installation.
After installing the ifupdown2, everything went back to normal on both systems.
So once again, thank you proxmox for your lousy work! Now get back to work and do it properly this time. Or at least inform people of that!
To all the others: do not perform upgrade unless you have physical or kvm access to the systems!!!!!
(and some experimented users like @denuin come for help other when they have an idea. Your're just purging your hate here. That will doesn't help