Quick answer
What to do first
Build 42 supports multiplayer. For a small group playing together, use Host and keep the hosting player online. Join an existing server if its owner handles the world, or choose a dedicated server when the group needs independent availability. Everyone must match the server's build and required content before troubleshooting invitations.
Check your game conditions
- Current Stable
- 42.20.4 Stable
- Play mode
- Multiplayer (Host or dedicated server)
- Vanilla / Mods
- Vanilla baseline; mods may replace rules
- Sandbox / server settings
- All players and the host must agree on build, mods and world rules; Host requires the host to remain online.
Which session fits your group?
| Situation | Choose | Check first | Responsibility |
|---|---|---|---|
| Everyone plays at the same time | Host | The hosting machine can remain running | The host starts and stops the session. |
| A friend already runs the world | Join that server | Build, address/invite, credentials and mod list | The owner controls rules and access. |
| Players need independent schedules | A dedicated server | Who maintains updates, backups and availability | The server owner, not any one player, maintains the process. |
| Someone wants to keep an old world | Agree a retained branch first | Save compatibility and availability for every player | Do not update only one participant and expect the old world to convert. |
Agree the world before sending invitations
Record the branch, any required mods, the chosen world and the basic survival settings. Starting from vanilla reduces the number of causes if your first session fails. Add third-party content only after checking that its author supports your build.
For Host, create or select the intended server profile rather than accidentally starting a different world with similar settings. Invite your friends using the supported Steam/session interface. Joining a dedicated server may instead require its address, ports and server password from the owner.
Confirm that everyone joined the same world
Check the build and world rules together after joining. A client's solo Sandbox settings do not override a server. Agree where to meet and store shared supplies; joining successfully does not place everyone in the same safe location.
If joining fails, note the stage: host startup, reaching the server, or rejection during loading. Follow the connection guide for that stage instead of repeatedly rebuilding the world. Back up established progress before changing mods or branches.
Version notes & limits
The original December 2024 B42 launch was singleplayer-only; multiplayer arrived later. Current 42.20.4 Stable is the starting branch here, not the old unstable-only status.
Host/join planning and first-session checks, not server purchasing, OS installation or a guarantee that every network setup will connect.
Last verified means the linked documentation was reviewed, not that this guide was tested in-game. PZwiki is maintained by community contributors.
Version & sources
Sources & what may change
- Applies to
- 42.20.4 Stable; Multiplayer (Host or dedicated server); Vanilla baseline; mods may replace rules
- Last verified
- 2026-09-04
- When to check again
- A relevant Stable patch, changed world setting, mod update or correction to the cited instructions.