Ensure the version of the world matches the Minecraft version running on the Minecraft server.

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Finding a singleplayer world from your computer

If you wish to upload a singleplayer world from your computer to a Minecraft server, follow these steps:

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On Windows:

  1. Enter Windows Key + R on your keyboard and enter %AppData%
  2. Head to the .minecraft folder and then /saves
  3. Locate the world you wish to upload, and archive the folder with a tool like WinRAR or 7Zip

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On a Mac:

  1. Navigate to ~/Library/Application Support/minecraft folder by pasting the file path on your Mac’s Spotlight
  2. Right click the world folder, and select “Compress [fileName]“

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Uploading the world to your server

  1. Stop the server
  2. Upload the world archive to the File Manager on the dashboard
  3. Select the three dots beside the file, and click “Unarchive”
  4. Modify the level-name value in server.properties file to the name of the world folder
  5. Start the server!

And voilà, you should now be able to use and play your custom world on your Minecraft server!