I am playing Minecraft on Ubuntu, running it with the following command (in a bash file)

padsp java -Xms1024M -Xmx1024M -Djava.net.preferIPv4Stack=true -jar /home/lagerdalek/Games/Minecraft/Minecraft.jar

Over the last 4 weeks I have lost 5 worlds.

This is not the problem where a world is no longer visible from the menu, and I need to rename level.dat; rather, it is visible as a save game, but when I open it, it is a new, freshly generated world! Once it was the chunk I had saved with all other chunks deleted, but otherwise it is new.

Minecraft had not crashed, rather I had saved the game and exited by closing the window.

This is getting very annoying. If anyone else is suffering from this problem, have you found a work around? Should I back up saves after I finish a game or is it too late by then?

2 Answers 2


One work around is to run your own Minecraft server. The a dis-advantage this the Nether isn't currently working. You can launch the Minecraft server to load single player worlds. Just find your old ./world# folder in your .minecraft directory. When launching the server be sure your world matches the world name in the server.properties file.

I believe Mojang mentioned going this route in the future with Single player. Having the client launch a server instance locally and connect to it.

When this is fixed in future versions it should be a simple copy of the ./world folder back to your .minecraft directory and you will be able to load the world normally again.


After much testing I narrowed this down to a firewall problem.

When I run ufw (the vanilla Linux firewall), it was a regular occurence, now, not any more.

It's not so good running without a firewall, but my start up minecraft bash script stops it for me, and I just have to remember to turn it back on again afterwards :(

Why the firewall deleted worlds for me, I don't know. I suspect it is related to the randomly moving spawn point bug, which Notch claims is fixed, but I don't want to risk losing my 5 month old world just to test it.

  • 2
    you could try using something like inotify to write a script that regularly backs up your savegame while you play minecraft with the firewall turned on, maybe you can then even localize the event responsible for the deletion
    – Zommuter
    Jul 8, 2011 at 4:50

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