Change your Minecraft version or server software

A new Minecraft release comes out, your friends update their game, and suddenly nobody can join. Or you want to move from Spigot to Paper, or try Fabric. The Versions page in the panel swaps your server software and Minecraft version in a couple of clicks.

The click is the easy part. What matters is what happens to your world, your Java version and your plugins or mods, so read the whole guide before changing anything.

What the Versions page does

Open your server, then the Minecraft group in the sidebar, then Versions. The page has a Filters box with Fork (the server software), Version Type, Search and Current Version, and a list of Minecraft versions on the right.

When you install a version, the panel:

• force-stops the server, without letting it save;
• deletes the libraries folder, or every file on the server if you turn on Delete Existing Files;
• downloads the new software as server.jar (some types come as an archive, which it unpacks) and points the server's jar setting in Startup at it;
• writes eula.txt if you turn on Accept EULA.

Everything else stays: your world, server.properties, plugins, mods and configs. The panel does not start the server afterwards, and it does not change the startup command or the Java version. Those two details explain most of what can go wrong.

Why upgrades only go one way

Every world remembers which version saved it last. When a newer version loads it, Minecraft upgrades the world's data to its own format, chunk by chunk, and saves it that way. Older versions were never written to read the newer format.

So moving up is normal, but moving back down is not supported. Paper and its forks refuse to load chunks saved by a newer version and stop with an error rather than risk damage. Other software may load the world anyway and lose chunks, blocks or items in the process. Blocks and items that only exist in the newer version disappear either way.

Snapshots, listed when you set Version Type to Snapshot, are test builds. Mojang warns they can damage worlds, and almost no plugins support them. Use them on a copy, not on the world you care about.

The only real undo is a backup from before the change.

Back up first

1. Press Stop in the console and wait until the server has stopped. The Versions page kills the process, so stopping it yourself is what saves the world properly.
2. Open Backups and click Create backup. Each server has one backup slot; if it is taken, download the old backup and delete it first.
3. For extra safety, download the world folders over SFTP too.

With a backup in place, a failed upgrade costs you a few minutes instead of a world. The backups guide explains how to restore one.

Change the version step by step

1. With the server stopped and backed up, open Versions.
2. Check Fork first. The page preselects the software it thinks you are running, and that guess is often wrong (see Common problems). Choose the software your server should run, such as Paper.
3. Set Version Type to Stable and type the version you want in Search, for example 1.21.1.
4. Click the version. In the window, Select Build preselects the newest build, which is normally the right choice.
5. Under Options, leave Delete Existing Files off to keep your world. Turn on Accept EULA if you accept Minecraft's EULA.
6. Click Install Version and wait for the message that the update started.
7. Press Start and watch the console.

Starting begins a renewal period, so keep the panel open. If the node is full, Start puts you in the start queue first.

Switching to different software

The same page changes the software, not just the version. What to expect:

Paper, Purpur, Spigot and Fabric all start from a single server.jar, so the page can move between them. NeoForge and Forge start differently, and the Versions page does not change the startup command, so a new server of that type is the reliable route; it also comes with the right Java version and access to the Max plan.

The Fork list also contains proxies such as Velocity, BungeeCord and Waterfall, and small "limbo" servers. They do not run a world, so do not pick them for your game server.

Pick the right Java version

Each Minecraft version needs a particular Java:

Our Paper, Purpur, Spigot and Fabric servers start on Java 25, NeoForge on Java 21 and Forge on Java 17. Going forward on those is usually fine. Going back to an old version is where Java breaks things.

When the console detects a Java mismatch, an Unsupported Java Version window appears: choose a version and click Update Docker Image. It does not catch every case, so if the server crashes right after an older version change, set Java yourself under Startup → Docker Image and start again.

Plugins and mods after the change

Your plugins and mods are not touched by the change, which also means none of them are updated. Every plugin has to support the new version, and every mod has to be rebuilt for it.

Before upgrading, check that your important plugins or mods already have a release for the target version. Afterwards, install the new releases with the Plugin Manager or Mod Manager and delete the old files, since installing does not replace them.

Players also need a matching game version. On a modded server, they need the updated mods too. On Paper and its forks, the ViaVersion plugin lets players on newer Minecraft versions join an older server, which buys you time to wait for your plugins to catch up.

Common problems

Current Version shows the wrong software or version

The panel only knows for sure what it installed through this page. Before that, it guesses from your files, and when it cannot tell, it shows a placeholder such as VANILLA 1.20.4. Trust the console's startup lines instead, and always check Fork before installing.

The server will not start after the change

Usually Java. Use the Unsupported Java Version window if it appears, or pick the version from the table above under Startup → Docker Image.

A window asks me to accept the EULA

Accept EULA was off. Click I Accept in the window and start the server again.

The world is new, or the Nether and End are empty

If Delete Existing Files was on, restore your backup. After switching from Paper to Fabric, the Nether and End are still in world_nether/DIM-1 and world_the_end/DIM1; with the server stopped, move those DIM-1 and DIM1 folders into world. Paper and Spigot sort this out by themselves when you switch the other way.

Plugins throw errors after an upgrade

They are built for the old version. Update them, or remove the ones without an update yet and restart.