Upgrading without loss of data

I’ve been using Penpot on my NAS with pleasure. Recently I upgraded using docker-compose, which went well. But, as I was half-expecting, my data was lost: user was gone, designs and projects were gone: it was a fresh installation. How do you guys preserve the data? I’m terrible at docker, even though I’m a webdeveloper and server admin, I just never got around to digging into it. So: how do you work around this? Is there a workflow you could recommend?

Have you looked at the Technical Guide?
You may find more info in Install with Docker under Update Penpot.

Can you describe what commands you used to perform the update?