I have a forge MC server running on Ubuntu using VirtualBox and I'm trying to put my single player map onto the server. When I drag the map into the server directory it seems to be completely different. I don't spawn anywhere near the worldspawn and I can't teleport to the worldspawn because it appears to not even exist.
Why is my map not working?
1.12.2 created map (I have used and saved it using a 1.15.2 client)
Basically, I found out that my map wasn't working because I had used the "Drag'n'drop" feature of VirtualBox. This copied the folder, but did not copy the contents of the folder! Basically, I had an empty map folder.
You can fix this by sharing a folder with your guest Ubuntu installation, adding the Ubuntu user to the virtualbox share folder group, restarting Ubuntu, and moving the map folder into your server directory.