How to upload a world to a Minecraft server

You have a world on your computer or on another host, and you want it on your server. The steps are the same everywhere.

1. Find the world folder

From a single-player game: open the Minecraft launcher, Installations, the folder icon, then saves/. Each folder there is a world.
From another server: the folder named by level-name in server.properties, usually world.

A Java world folder has files like level.dat, region/ and playerdata/. For Java servers, the Nether and End are inside the same folder (DIM-1 and DIM1) on Vanilla and Forge. On Paper-based servers they can be separate folders (world_nether, world_the_end); copy those as well.

2. Stop the game

Stop the server first so it does not save over what you upload.

3. Zip and upload

Compress the world folder into a .zip file. On Saryno open Files, upload the zip, and use Extract. For big worlds, use SFTP, which is faster and can resume.

4. Point the server at it

Either name the folder world, or set it in server.properties:

level-name=MyWorld

If a world folder already exists, move it aside or delete it, otherwise the server uses the old one. Saryno's World tab can swap worlds and keeps the one you replaced.

5. Start and check

Start the game and look at the console for "Preparing level" with your world name. Join and check your build is there.

Common mistakes

A folder inside a folder. After extracting, level.dat must be directly inside the world folder, not inside another folder.
Version too old or too new. A world made on a newer version cannot be opened on an older one. Match the server version to the world, see changing your server version.
Bedrock worlds are different. A Java world does not open on Bedrock or the other way round.
Players start at spawn. Player data is in playerdata/; keep it if you want inventories and positions to carry over.