Switching a Hytale server to the pre-release patchline without losing your world

Hytale ships two patchlines. Stable is what the launcher installs by default. Pre-release carries content that has not reached stable yet, and it moves a lot faster. Running a server on pre-release is the only way to see new zones, items and biomes early, and it is also the fastest way to lose a world if you do it in the wrong order.

This is the order that does not lose worlds.

Before you touch anything: know what you are risking

Two things break when a patchline changes underneath a running server.

The first is world data. A pre-release build can change how world data is written. Once a newer build has opened your universe/ directory and written to it, going back to the older build is not guaranteed to work. Treat the switch as one-way unless you have a copy.

The second is client compatibility. A client on the stable patchline cannot join a server on pre-release. The moment you switch the server, everyone who plays on it has to switch their launcher patchline too, in Settings, and reinstall. If you do that without warning on a Friday evening, you have not upgraded your server, you have taken it offline for everybody who did not read the message.

The sequence

1. Snapshot the world first, deliberately. Not "there is a nightly backup somewhere". Take a snapshot now, and confirm it exists before you go any further. On a Passim IT server this happens automatically before a branch switch, but take a manual one anyway when the world matters to you - the cost is a few seconds and the alternative is a conversation you do not want to have with your players.

2. Pull a copy off the server. A snapshot on the same platform protects you against a bad build. A copy on your own machine protects you against everything else. Download the universe/ directory over SFTP. It is the only artefact that is genuinely irreplaceable: server binaries, assets and mods can all be fetched again, and your world cannot.

3. Write down what you are running. The current patchline, the build you are on, and the exact list of mods in mods/ with their versions. When something breaks two builds later, the useful question is "what changed", and you can only answer it if you recorded where you started.

4. Tell your players, with a time. "Server moves to pre-release on Saturday at 14:00 CET, you will need to switch your launcher patchline to pre-release and reinstall before you can join." Specific enough that nobody is confused, early enough that nobody is surprised.

5. Stop the server properly. Use the console stop command or the panel's stop button, and wait for it to finish. Killing the process mid-write is how you corrupt a chunk that was fine a second earlier.

6. Switch the branch, then start it. On a managed panel this is a dropdown: install branch, pre-release, save, start. If you are self-hosting, that means fetching the pre-release archive with the Hytale Downloader and replacing HytaleServer.jar and Assets.zip before you restart.

7. Read the first thirty seconds of the console. Not the last line - the whole startup. Mod loading errors, missing assets and world-format complaints all appear there, and they appear before anything visible goes wrong in-game. If the console looks unhappy, stop and roll back while the only thing you have lost is ten minutes.

8. Walk the world before you invite anyone in. Load the areas people actually built in. A world that starts is not the same as a world that survived.

When it does go wrong

Roll back, immediately, before anyone plays on the broken state. Every hour of play on a world you are about to discard is an hour you will have to ask people to repeat.

On a Passim IT server, restoring a snapshot is a panel action: pick the snapshot, confirm, and the server restarts on it. The world you rolled away from is kept until you overwrite it, so a rollback is itself reversible - if it turns out the problem was a mod rather than the build, you have not thrown away the newer state.

Then switch the server back to stable before you re-open it, and treat the pre-release attempt as information rather than a failure: you now know which of your mods does not survive that build, which is exactly the thing the pre-release patchline is for.

The honest summary

Pre-release is a test branch on a game that entered early access in January 2026. It is worth running if you want to see what is coming, and it is a bad idea for the server your community actually lives on. The pattern that works is two servers: a small pre-release one you are willing to break, and the stable one you are not.

If you would rather ask a person than read release notes, that is fine too - you get the owner, not a script.