Worlds and datapacks

You manage worlds in your Minecraft server's Worlds tab and datapacks in its Datapacks tab. A proxy such as Velocity has no world and so neither tab.

The loaded world and the others

At the top is the world the server loads, with version, game mode, difficulty, size, dimensions, players so far and seed. Below are the Other worlds on the server. Load picks one of them; the server loads it at the next start, and Restart now does that right away. The previous world stays, so you can switch back at any time.

Create a new world

1. 1

   Press New world and enter a name (up to 40 letters, digits, dot, - or _).

2. 2

   Enter a seed, roll one, or leave the field empty for a random one.

3. 3

   Under Advanced you choose the world type (Default, Large Biomes, Amplified, Superflat), game mode, difficulty, whether structures are generated, and hardcore.

4. 4

   Create and load picks the new world at once; Create only keeps it for later. The game generates it at the next start with this world.

Game mode and difficulty apply to the whole server while this world is loaded.

Upload your own world

Pack the world folder (for example from your game's saves folder, the folder with the level.dat) as .zip or .tar.gz and upload it under Upload world. The size limit is shown there; upload larger worlds over SFTP. The portal checks that the archive really holds a Minecraft world.

Download and delete

Download packs a world into an archive; the link works once, and the archive is deleted an hour later. Delete permanently removes a world that is not loaded, with its Nether and End, with a backup first if you like; your existing backups stay. The loaded world cannot be deleted, and one the server is still running until its restart only afterwards.

Datapacks

Datapacks belong to a world, not to the server software. The Datapacks tab finds them on Modrinth and puts them into the loaded world's datapacks folder; after switching worlds, that world's own datapacks apply.

• Search and install under Discover; see, update, switch off and on or remove them under Installed.
• A new datapack is listed with “loads at the next start”: the server loads it then.
• If one says “turned off in the world”, Enable switches it on through the console; the server has to be running for that.
• Update automatically checks for new versions every six hours, effective at the next restart.
• Put your own datapacks as a .zip into the world's datapacks folder with the file manager or SFTP.