Minecraft – trying to copy a single player minecraft world onto a server

There is a number of things you should rule out first:

• Are you able to login through http://account.mojang.com/login?

• Are you using the proper client from http://minecraft.net/download?

• If you were able to login with your old computer; make sure your current one doesn't have any firewall blocking internal / external connections.

• On the computer with the issue, do the following:

  : Go to this url, and substitute USER for your actual username and substitute PASS for your actual password.

  : It should output a Session ID (a bunch of numbers and letters), if not; and it returns Bad login or another exception; contact mojang.

You should create a symbolic link between the two folders (saves and the saves folder on your USB drive). Instructions on doing this with your Minecraft worlds are shown at http://minecraft.gamepedia.com/Tutorials/Saved_data_Dropbox_guide_saves_only. Instead of using dropbox as your destination folder however, you can use a folder on your USB drive. The quote below from the Minecraft Wiki (link above) shows you how to do this on Mac OS using the terminal.

ln -s ~/Dropbox/Minecraft/saves ~/Library/Application\ Support/minecraft/saves

Replace ~/Dropbox/Minecraft/saves with the destination folder.