Change your Minecraft server version safely

Before you start

1. Take a backup. Create and download a backup.
2. Stop the server from the Console.
3. Check that your plugins and mods support the new version. Plugins built for 1.20 often don't load on 1.21 until they are updated.

Upgrading

1. Open Server Versions, choose your software and the new version, and Pull to Server.
2. When the download finishes, start the server and watch the console for errors.
3. Update or replace any plugin that reports an incompatibility.

Downgrading

Minecraft worlds generally cannot be loaded by an older version once a newer one has opened them. To go back, restore a backup taken before the upgrade.

Java version

Newer Minecraft versions need newer Java. The Server Versions details panel shows the Java version a build expects; if the server refuses to start with an "unsupported class file version" error, the Java version is the problem. Check the Startup tab for a Java-version variable; if there isn't one, open a ticket and we'll switch it for you.

Testing first

If your community is large, copy the server files to a second small server, test the upgrade there, and only then repeat it on the live one.