Discourse / AUFS / Ubuntu Upgrades

I tried to upgrade my OS on the digital ocean droplet I created for Discourse a few years ago and received the following error:

Sorry, this storage driver is not supported in kernels for newer
releases

I’m running Ubuntu 20.10 and upgrading to 21.04

  1. What is AUFS used for, it seems used heavily for the docker setup.
  2. Is there any guidelines on how to migrate to the new OS? Or is an older kernel that supports aufs required/ different distribution?

We used to default to aufs as the other docker storage driver (devicemapper) was really bad. Nowadays Docker defaults to overlay2 and that is also completely okay to use!

21.04 isn’t recommended for servers. It isn’t supported for very long. I’d stay with an lts release.

And the problem you describe is probably easiest resolved by just spinning up a new server and doing a clean install.