Proxmox LXC backup with exit code 11

In case you have some LXC containers on your Proxmox server, then there is high chance that you will get some errors during backup them up. Some container templates may not support snapshot or suspend modes. Instead you should you use stop mode. It is important to remember that during such backup container will be stopped, so be aware of that in case you have some encryption which could ask for a key during startup.