Each Minecraft version needs a certain Java version. If your server crashes with an error about Java, or UnsupportedClassVersionError, the Java version is usually the problem.
Which Java do I need?
- Minecraft 26 and newer: Java 25
- Minecraft 1.20.5 to 1.21.x: Java 21
- Minecraft 1.17 to 1.20.4: Java 17
- Minecraft 1.16.5: Java 16
- Minecraft 1.12.2 and older: Java 8
If you're not sure, pick the newest Java your Minecraft version supports.
Change your Java version
- Open Startup in the menu on the left.
- Your Java version is in the box on the right. There's a handy guide underneath it.
- Choose the Java version you need from the list. For example, for a 1.21 server, choose Java 21. It saves straight away.
- Restart your server, so the new Java version is used.
Good to know
- Installing a modpack from the Modpacks page sets the right Java version for you. See Install a modpack.
- Upgraded your Minecraft version? You may need a newer Java too. See Upgrade your server version.
