Errors while loading a map
The world will not open at all. Usually a version it cannot read, occasionally an unpacking mistake.
Check the obvious one first
Open the saves folder and look at the world folder. Inside it there must be a file called level.dat. If instead you see another folder with the same name as the first, you unpacked one level too deep — move the inner folder up and the world appears. If level.dat is sitting loose in saves next to your other worlds, you unpacked one level too shallow.
The other causes
- The world was made in a newer version than the one you are running. Minecraft refuses rather than guessing, and it is right to. Launch the version the map's page lists.
- The download did not finish. A truncated .zip often unpacks far enough to look complete and then fails on load.
- level.dat is corrupted. Minecraft keeps a spare called level.dat_old in the same folder — rename it to level.dat and try again.
- The world needs a mod loader or a specific modpack, and you opened it in vanilla.
What to do
- 1Match the version first — it costs a minute and explains most of these.
- 2Download the file again from My purchases and unpack the fresh copy, in case the first one was cut short.
- 3Try the level.dat_old trick if the game names that file in its error.
- 4Send us the error text and the map name if none of it helps. A message with the actual error in it gets a real answer straight away; a message saying it does not work needs three rounds of questions first.
A world converted to a newer version cannot be converted back. If you want to keep playing on the old version, keep a copy of the folder before you open it on the new one — the upgrade happens on first load, without asking.