When using /maps, the plugin throws an error. https://hasteb.in/axobidap.md

This is very unlikely. I didn't achieve to get the same error make sure to use this version of the plugin: https://www.spigotmc.org/resources/imageonmap.26585/download?version=314302

This version works, thank you.

That was really, really weird as these versions are exactly the same:

$ sha1sum ImageOnMap*.jar
49d027ba2e98387d7ee6eaf4a16d9d1021ab3f6a  ImageOnMap-4.0-pre2-gh.jar
49d027ba2e98387d7ee6eaf4a16d9d1021ab3f6a  ImageOnMap-4.0-pre2-spigot.jar

But well, it works, so that's fine, let's hope we don't have the same problem again :)

What is your version? And you are on paper ?

This server is running Paper version git-Paper-105 (MC: 1.15.2)

Did you build the .jar yourself?

No, I downloaded the plugin from the Releases tab

That's weird. We'll look into it… This bug should have been fixed long ago and /maps is working on our side. Maybe an edge case…

This can't happen because of a datapack with achievements installed on the server?