The question every returning group asks: can we move our B41 server to Build 42? The honest answer, as of Build 42.20: your world can't come, your people can. Here's exactly what carries over, what doesn't, and the two reasonable paths — plus the backup you should take before touching anything.
What does and doesn't carry over
| Thing | Carries to B42? | Why |
|---|---|---|
| World/map save | No | B42 changed the map (basements, new areas), the save format and the simulation. B41 worlds are not loadable. |
| Characters & skills | No | Characters live inside the world save. |
| Your mod list | No — needs B42 versions | B41 mods are incompatible; most popular mods now ship separate B42 builds. See the Workshop mods guide. |
servertest.ini settings | Mostly — copy values, not the file | Most keys survive, but B42 added/renamed some. Generate a fresh B42 ini and port your values across rather than dropping the old file in. |
| Sandbox settings | Partly | Same approach: fresh servertest_SandboxVars.lua, re-apply your choices — B42 added new sandbox options the old file doesn't have. |
| The community | Yes | The part that matters. |
The instinct to fight is copying old files over new ones. A B41 servertest.ini dropped onto a B42 server mostly works, which is worse than not working — you silently miss every new B42 key. Diff, don't replace: the settings walkthrough covers what's new.
Path 1 — fresh B42 server (what most groups should do)
- Back up the B41 server anyway (below). You are ending an era; keep the artifact.
- Stand up a clean B42 server — the full walkthrough is the dedicated server setup guide.
- Rebuild the mod list from B42-tagged versions only. This is the step that takes an evening; do it before announcing a launch date.
- Port your ini and sandbox values by hand into the freshly-generated files.
- Launch as a proper wipe event. Zomboid groups take fresh starts well — day-one on a new map with the B42 systems is the most fun your server has had in years. Lean into it.
Path 2 — stay on B41 (legitimate, and time-limited)
The B41 branch remains available on Steam as a legacy beta branch, and a B41 server keeps running exactly as before — clients just select the same legacy branch in the game's Steam betas menu. Choose this if your world is genuinely irreplaceable and your group isn't done with it.
Be realistic about the trajectory: the mod ecosystem's energy has moved to B42, players drift to where the new content is, and every patch cycle widens the gap. Treat a legacy B41 server as a farewell tour, not a destination.
Don't try to run both on one box unless you size for it — two Java servers is two full heaps, and the RAM guide's numbers apply to each independently.
Porting your settings properly
The mechanical part of the migration is an evening's careful work:
- Boot the fresh B42 server once so it generates current-format
servertest.iniandservertest_SandboxVars.lua. - Open old and new ini side by side. Copy your values across for keys that exist in both — identity, password, player cap, PVP posture, backup settings. Leave new B42-only keys at their defaults until you've read what they do (settings walkthrough).
- Do the same for SandboxVars — and treat this as a design review, not a copy job. B42 added dials (animal populations above all) that your B41 file has no opinion on, and some old choices deserve rethinking against the new systems.
- Rebuild the mod list last, from B42-tagged Workshop items, dependencies first — the load order guide has the workflow. Resist porting the whole 80-mod list on day one; launch with the essential 20 and re-add deliberately.
Running the switch as an event
Groups that migrate well treat it as a launch, not an outage:
- Announce a date a week out; let people finish (or dramatically fail) their B41 stories.
- Final-night send-off on the old world — a horde night, a last stand. Then the backup, then lights out.
- Day one together: fresh B42 map, everyone level 1, the new systems (animals, basements) landing on the whole group at once. This is the most multiplayer fun the game has shipped in years — the wipe is the feature.
- Keep the B41 backup forever. Six months on, hosting a one-night "museum server" from it is a great community event.
The backup, before anything
From the B41 server, copy somewhere safe:
~/Zomboid/Saves/Multiplayer/<servername>/ # the world
~/Zomboid/Server/<servername>.ini # server config
~/Zomboid/Server/<servername>_SandboxVars.lua
(Default <servername> is servertest; adjust for -cachedir if you moved it.) Stop the server first, or at least /save from the console immediately before copying — a save copied mid-write can be corrupt. That folder set is a complete, restorable B41 server: keep it and the option to revisit the old world never expires.
Frequently Asked Questions
Can I load my B41 world save on a Build 42 server?
No. As of 42.20 there is no conversion path — B42's map and save format are different, and the game does not migrate B41 multiplayer worlds. A B42 server starts fresh.
Can my group keep playing our B41 world at all?
Yes — B41 stays available as a legacy beta branch on Steam, and clients on that branch can keep joining a B41 server indefinitely. It just won't get new content, and the mod ecosystem is moving on.
Will my B41 mods work on the new server?
Not the B41 builds of them. Most major mods have shipped B42 versions — rebuild your list from B42-tagged Workshop items, libraries first. The mods guide covers the syntax and the traps.
Should we wipe or wait for a converter?
Plan on the wipe. Nothing announced suggests B41→B42 world conversion is coming, and the groups that thrive treat the B42 move as a launch event rather than waiting on a maybe.
Starting fresh is the natural moment to stop self-hosting the admin work too — our B42-ready Project Zomboid servers come up on the stable branch with backups included, so the new era starts with the safety net already on.
