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Change the Minecraft version

Update to a new release or go back to an older one on Paper, Fabric, Forge and NeoForge, without losing the world.

1 min readUpdated 2026-09-14Diese Anleitung auf Deutsch lesen →
  1. Backup first. Worlds are upgraded when opened by a newer version and cannot be opened by an older one afterwards.
  2. Server → Startup. Set the version variable:
    • Paper: MINECRAFT_VERSION (e.g. 1.21.1; latest = newest release).
    • Fabric: MC_VERSION plus, if you want a specific loader, LOADER_VERSION.
    • Forge: MC_VERSION and FORGE_VERSION (recommended build type picks a stable one).
    • NeoForge: MC_VERSION and NEOFORGE_VERSION.
  3. Server → Settings → Reinstall. This downloads the new server jar. Your files stay.
  4. Start. Check that plugins and mods support the new version. The console lists the ones that fail to load. Update those through the installer.

Java version

Minecraft 1.21+ needs Java 21, 1.18-1.20.4 Java 17, 1.17 Java 16, older versions Java 8. The Docker image (Startup → Docker Image) sets the Java version; pick the matching one when you change Minecraft versions. Modpacks installed through our installer set it for you.

Downgrading

Only with a world from before the upgrade. Restore the backup you made in step 1, then follow the steps above with the older version.