Your Barotrauma crew just survived a hull breach, patched the reactor, and limped into the next outpost - a great note to stop on. Next session, half the crew is online and ready to push further into the trench, but the person who hosted last time isn’t around. So the sub sits docked.

If you’re self-hosting rather than renting a dedicated server, that’s not a bug - it’s just how Barotrauma’s campaign save works.

Why Barotrauma Needs the Original Host

A self-hosted Barotrauma multiplayer campaign saves to the host’s machine, under %LOCALAPPDATA%\Daedalic Entertainment GmbH\Barotrauma\Multiplayer, as a <save_name>.save file plus a matching <save_name>_characterData.xml. Whoever hosted holds both files, and without them nobody else can load that campaign - your crew’s talents, sub upgrades, and campaign progress simply aren’t on any other machine.

The Real Fix: Put the Save on More Than One Machine

The fix isn’t finding a way around the host requirement - it’s making sure more than one PC actually has the save. If any crewmate had a current copy of both files, they could load the campaign and host themselves.

That’s what SaveSync does. It keeps your Barotrauma campaign save - the .save and its _characterData.xml together - synced across every PC in the crew. Whoever hosted last syncs automatically when the session ends; whoever’s free next pulls the current save and hosts. One player being offline stops being the thing that grounds the sub.

How to Set It Up

  1. Everyone who might host installs SaveSync on PC.
  2. Create a sync group and invite the crew.
  3. Select Barotrauma in SaveSync - both save files are picked up as a pair.
  4. Share it with your crew so everyone’s on the same campaign.
  5. Play normally. SaveSync syncs the save after each session wraps.
  6. Anyone loads the current campaign and hosts the next voyage - no waiting on one specific captain.

Don’t Lose Progress in the Handoff

The fastest way to sink a good campaign isn’t a hull breach - it’s someone hosting from a stale save and quietly erasing a session’s worth of progress or crew upgrades. SaveSync avoids that by syncing the newest save after every session and keeping history, so a bad run can be rolled back instead of accepted as permanent.

Keep the Voyage Going

Barotrauma throws enough at your crew without “the host is offline” adding to the list. Get the save onto every machine, and any available crewmate can take the sub out.

For the full setup, see the Barotrauma save sharing guide. To spread hosting duty evenly instead of relying on one player, read the Barotrauma host rotation guide. SaveSync works the same way across every supported co-op game - one purchase covers them all.