Proxmox failed container backups

Proxmox failed container backups

As you probably know by now, I am very keen on backups. I even back up my Backups and then back up those too…maybe I have a problem.

Anyway, my Proxmox container backups kept failing each night. However, VM backups ran without a problem, so I was slightly confused. Initially, I thought it must be a problem with my backup infrastructure, but after viewing the backup logs, it reported that it could not access a ‘tmpdir’ folder.

I didn’t and still don’t understand why the same backup program works for VMs but doesn’t work for containers. However, a little Googling found the fix.

On each Proxmox server, you have to edit the /etc/vzdump.conf file. By default, there is a line that looks like this: –

#tmpdir: DIR

This needed to be updated to be: –

tmpdir: /tmp

Note the ‘#’ has been removed, too – the original line is a comment line.

After making those changes, container backups worked fine.

One thing to note is that the volume on which /tmp lives must have sufficient free space for the backups / compressed files, etc. In my case, I install Proxmox on a decent-sized SSD, and my containers aren’t very big, so I don’t foresee any problems.


Hi, my name is Stephen Finchett. I have been a software engineer for over 30 years and worked on complex, business critical, multi-user systems for all of my career. For the last 15 years, I have been concentrating on web based solutions using the Microsoft Stack including ASP.Net, C#, TypeScript, SQL Server and running everything at scale within Kubernetes.