Introduction

Project Zomboid's multiplayer is a blast – surviving the apocalypse is just better with friends. Build 41 has long been the stable version powering co-op and PvP adventures, complete with a rich mod ecosystem. Build 42, on the other hand, is the ambitious new update in testing, packed with features but (for now) single-player only. If you're confused about how to set up multiplayer, which build to use, what's new in B42, or how mods and servers are affected – don't worry. This guide covers everything you need for a deep dive into Project Zomboid multiplayer in B41 and B42.

Let's start by understanding the big picture: Why does Build 42 not have multiplayer yet, and what does that mean for you and your friends?

Build 42 Multiplayer Status – Why You're (Currently) Stuck in Single-Player

If you've opted into the new Build 42 unstable branch expecting to jump into multiplayer, you've likely had a surprise: the "Invite Friends" or "Host" buttons are missing. The hard truth is that Build 42 has no official multiplayer support at this time. The Indie Stone (developers) intentionally disabled multiplayer in B42 while it's in testing, focusing on single-player first.

This has led to some confusion (and disappointment!). Some eager players even set up dedicated servers for B42 only to realize they can't use them yet. The devs removed the MP code temporarily, so it's not just a matter of bugs – the feature is actively turned off until further notice.

Why remove multiplayer?

Based on dev commentary and community discussions, there are a few reasons:

• 🆕 Massive New Features: Build 42 brings tons of new systems (we'll detail them later). The devs want to test and balance these in single-player first before adding the complexity of networking. It's easier to debug one thing at a time.
• 🔧 Performance Optimizations: Early reports from B42 show significantly improved performance in single-player. One player noted, "The performance is amazing! I can actually run this game on my work laptop now at a consistent 60fps!". The devs likely want to ensure the game runs smoothly solo before stressing it with multiple players.
• 🐛 Fixing Old MP Issues: Project Zomboid's Build 41 MP, while awesome, had its share of glitches. For example, a common complaint: "Even with good connection, cars driven by players close to each other often result in desynchronized collisions." Or the infamous zombie lag teleports. TIS doesn't want to carry these over. They're probably overhauling netcode to address desync and other MP problems in the B42 cycle.
• ⚔️ The PvP Problem: Let's face it, PvP in PZ has never been great. "PvP kinda sucks… Not kinda, it does suck," as candidly put by players. The combat rework in B42 (new aiming system, etc.) is partially to improve this. Devs might be adjusting player-vs-player mechanics (hit detection, balancing firearms) before flipping the MP switch back on.
• 🕒 Avoiding Bad First Impressions: B42 is unstable – bugs are expected. If they enabled MP now and it was a disaster (crashes, exploits, etc.), it could sour players on the new version. Better to delay multiplayer than release it half-baked and frustrate people. As the devs said, it's "unstable for a reason."

For now, Build 41 remains the multiplayer mainstay. "Build 41 is totally fine and working and the only option for MP," one Redditor confirms. So if you want to play with friends today, stick with Build 41 (the stable branch). The good news is B41's multiplayer is well-polished and quite stable after years of updates, offering that classic Project Zomboid co-op survival we love.

Later in this guide, we'll discuss workarounds to scratch the multiplayer itch in B42 (like split-screen or using Parsec). But first, let's ensure everyone knows how to get a multiplayer game going on Build 41, since that's where MP is alive and well.

Setting Up Multiplayer in Build 41 (Stable) – Hosting, Servers, and LAN

Build 41 has a fully functional multiplayer system, but setting up your game for co-op can be daunting if you've never hosted or used dedicated servers. Fear not – we'll walk through several ways to play multiplayer in B41:

Option 1: Host a Local Co-Op Game (Easy Mode)

If you just want to play with a few friends and don't need a 24/7 server, the game's built-in Host function is the quickest route:

1. Launch Project Zomboid (Build 41) and click Host. This brings up the Host Game menu. Here you can create a new server settings preset or use default. Give your server a name and set a password if you want.
2. Tune the Sandbox Settings (optional). You'll see an interface to adjust world options (zombie count, loot rarity, PvP on/off, etc.). You can save these settings for re-use. For a first run, the defaults are fine.
3. Start the server. The game will briefly show a console as it loads the server in the background, then drop you into the game as a player.
4. Friends join via Steam Invite or the Server Browser. As the host, once you're in-game, your Steam friends can right-click your name and Join Game. Or they can go to Join > Internet and find your server name (if you set it public). They'll need the password if you made one.

This "Listen Server" approach is user-friendly – it runs the server and client together. However, note: if the host player disconnects, the server goes down for everyone. It's perfect for a co-op session among friends, but not for a persistent world.

Local LAN play: If you're on the same local network (e.g. two PCs at home), one person can host as above. Others on the LAN can find the host's game under the LAN tab in Join menu. This doesn't require port forwarding or internet – just that the computers can see each other on the network. (Ensure any firewall prompts are allowed.)

Option 2: Run a Dedicated Server (More control, persistent world)

For a server that stays up independent of any one player, you'll want a dedicated server. You can run this on your own machine, a spare PC, or a rented server. The steps:

1. Install the Dedicated Server files. Easiest way on Windows: on Steam, go to Library -> Tools and install "Project Zomboid Dedicated Server". (On Linux, you'd use SteamCMD.) It's essentially a headless version of the game meant for hosting.
2. Initial launch and config files: Launch the server once to let it generate default files. It will create a Zomboid/Server folder in your user directory with config files (servertest.ini, SandboxVars.lua, etc.). Stop the server (press Ctrl+C in its console) once files are made.
3. Configure server settings: Open servertest.ini in a text editor. Here you can set the server name, player limit, password, etc. Important options:
   • DefaultPort – default is 16261 (UDP).
   • Public=true/false – whether to list on the public server list.
   • PvP=true/false – enable or disable PvP (you can also control safety zones in-game).
   • Administrator username/password – set an admin account to manage the server in-game.
   • Check SandboxVars.lua for world settings (or use PZServerSettings.exe for a GUI).
4. Port Forwarding: If players will connect over the internet (not just LAN), you must forward the necessary ports on your router to the server machine's IP. By default, Project Zomboid uses UDP port 16261 for the main connection, and UDP 8766 for Steam queries. After version 41.77, one additional port is used per player slot (16262, 16263, etc.) for direct connections.

   Minimal case: forward 16261 UDP and 8766 UDP. If you plan >1 player, also forward a range like 16261-16270 UDP to cover extra player slots (each client gets a port increment). If you skip this, players might get "Failed to connect" or see your server as offline.

5. Launch the server for real: Run the StartServer64.bat (Windows) or the shell script (Linux). The server console will appear and eventually say "Server started" with your configured name.
6. Players join: Give friends your public IP and port (or use the public server list if Public=true). They can use Join Server > IP tab to enter your IP and port 16261. Or find the server by name under Internet if listed (Steam must be working and you forwarded 8766 for it to show up on list).
7. Keep it running: The server will run until you close it. Many admins let it run 24/7 so players can join anytime. Check db and logs folder for info – errors, player info, etc. We'll cover admin commands shortly.

This dedicated setup is more involved, but it gives you persistent progress, and the host can log off while others continue playing. It's how larger community servers operate.

Option 3: Using a Server Hosting Provider (Easy but not free)

If you don't want to self-host, many game server providers offer PZ servers. The process there is usually:

• Rent a server from a host (make sure they support Project Zomboid).
• Use their web panel to configure settings (often a form or config editor).
• They handle the port forwarding and uptime. You just share the server IP:port and password with friends.

This costs money (a few dollars per month depending on slots), but can save time. It's essentially a dedicated server without you managing the hardware.

Administering Your Server (Build 41)

Once your server is up, you'll want to know some admin tools:

• In-game, an admin can press / to open chat and type commands. E.g. **/grantadmin <username>** to grant admin to a player, or **/teleport <user1> <user2>** to teleport user1 to user2. See the PZwiki for a full list of admin commands.
• Admin Panel (in-game): As admin, you have a debug icon on left. You can do things like invisible (ghost mode), edit player stats, spawn items, etc. Use these powers sparingly on a legit server – but they're great for fixing bugs (unstucking players, etc.).
• RCON: PZ servers support RCON protocol, which allows remote console access. The servertest.ini has an RCON password field – set it, and you can use an RCON tool to send commands to the server without being in-game. Useful for scripting or managing the server from afar.
• Logs and DB: The world's data is stored in servertest.db (a SQLite database for character data, etc.). Tools like DB Browser can open it if needed. The logs (console.txt etc.) show errors – always check these if something goes wrong.
• Server Options: You can tweak many settings live via the admin Panel (like change PvP on/off, adjust safemode, etc.). Some changes require a server restart to apply (like increasing max players or workshop mods).

One welcome addition in the 41.78 patch was the ability to check for mod updates via RCON – this helps to know if a server restart is needed when a mod updates on Workshop.

Now that we have Build 41's multiplayer up and running, let's compare it to Build 42's offerings and why you might still want to dip your toes into Build 42 (single-player for now) while hosting your multiplayer fun on B41.

Build 41 vs Build 42 – Feature Differences That Affect Multiplayer

Even though Build 42's multiplayer is disabled at the moment, it's useful to know what's new in B42 and how those changes will impact multiplayer once it arrives. Many players are asking "Should I play on Build 41 or 42?" – it boils down to stable multiplayer & established mods (B41) vs cutting-edge features (B42).

Here's a breakdown of the major differences and what they mean for gameplay:

Stability and Performance

• Build 41: Battle-tested over years. Generally stable MP, though big mods or 32+ players can strain it. Some known desync issues (zombies hopping a bit, car collisions mis-syncing) persisted but got better by 41.78. Performance in Build 41 can dip with huge hordes or mega-bases, but it's manageable. It's rare to crash if you and the server are set up properly. Essentially, B41 is the safe choice – if you want a long-running server or a smooth night of co-op, it won't let you down.
• Build 42: Bleeding-edge (unstable branch). Surprisingly, many players report B42 runs better on their machines than B41 did – the devs did a lot of optimization. However, B42 as an unstable build has frequent updates (which might introduce new bugs). You might hit weird issues – e.g., early B42 had a bug where melee hits could land from far away, which has since been fixed in a patch. There's also the risk of save corruption or required restarts on version updates (they warned that "save files made in 42 unstable will likely become unusable between now and 42 stable"). So, stability in B42 is about the evolving game state, not network stability (since no MP). If you play B42 now, treat it as an experiment – things can and will break/change until it goes stable.

Multiplayer stability: When B42 MP does drop, we expect it to be initially unstable too (likely an "IWBUMS" beta for MP), but eventually it should surpass B41 thanks to the groundwork being laid. The devs specifically mention wanting servers to run much longer without issues (one goal is to support multi-year in-game communities). So, in theory, B42 MP might handle huge maps, tons of player-built structures, etc., better than B41 MP does.

New Systems and Gameplay (What B42 Adds)

Build 42 isn't called a "transformative overhaul" for nothing. Here are key features and how they contrast with B41's status quo:

Which Should You Play Right Now?

It boils down to what you want:

To wrap this section up: Build 41 = proven, reliable multiplayer, with tons of mods and guides available. Build 42 = exciting new stuff, but you'll be going solo until multiplayer is reintroduced (and even then, mods and guides will take time to catch up). Many players decide to enjoy both – do stable MP on weekends with friends, and tinker in single-player B42 during the week, for example.

PvP and Co-Op Gameplay – Now vs Future

Project Zomboid can be played cooperatively or competitively (PvP), though co-op is by far the more common style on public servers (many disable PvP or have consensual PvP rules). Let's break down how PvP and co-op teamwork differ between Build 41 and what Build 42 might change:

PvP in Build 41: The Good, Bad, and Ugly

Co-Op and Team Dynamics

Co-op is where PZ shines. Build 41 co-op is basically the default way to play for many. You spawn together (or meet up), strategize who loots what, maybe designate roles (someone cooks, someone carpents, etc.), though the game doesn't force any specialization.

Community Tips for Co-Op Success

We've covered the gameplay and feature side extensively. Let's shift to something every MP player cares about: Mods! Specifically, which mods are essential for multiplayer, and how Build 42 throws a wrench in the works (temporarily) on that front.

Must-Have Multiplayer Mods (B41 & B42)

One of Project Zomboid's greatest strengths is its modding community. Mods can dramatically enhance multiplayer – from quality-of-life improvements to huge content additions. We'll highlight some of the best mods for B41 multiplayer, and then address the situation with B42 mods.

(Keep in mind: all players (and the server) must have the same mods enabled for MP. We'll note compatibility where relevant.)

Essential Mods for Build 41 Multiplayer

These mods are fan-favorites on Build 41 and have proven stable in MP:

(All the above mods are confirmed or generally known to work on Build 41 multiplayer as of the last stable update. Always check the Workshop page – look for notes like "updated for 41.73+" etc., which most have.)

The Build 42 Mod Conundrum

When Build 42 first dropped (unstable), the modding community faced a hurdle: the mod loader/format changed, breaking virtually all old mods. The devs basically refactored how Lua files are loaded (to support the new crafting and whatnot). So, none of the existing mods function in B42 until updated. As of early 2025, many popular mods have been updated or have beta versions for B42, but not all.

Must-Have Mods for B42 (that are available)

The community quickly developed some "B42 fix mods" to address glaring issues:

These were literally essential to play B42 comfortably, as noted by a Reddit user and echoed on PZFans. They "form the foundation of any B42 mod collection". If you jump into B42, install those first.

Beyond fixes, many quality-of-life mods have B42 versions now:

• Common Sense, Rain Washes Blood, Inventory tabs, etc. – Many of these have been updated or had analogues made. For instance, Push Cars, Shoulder Slot, Exercise with Corpses, Reload All, Generator Time, Map Drawing, Build 1 at a Time, etc., are available and working in B42.
• Content mods in B42: Some big mods began releasing B42 versions:
  • Brita's Weapon Pack now has a B42 patch (initially it didn't work due to model loading changes, but modders fixed it by early 2025).
  • Authentic Z was updated (so you can still have your fancy outfits in B42).
  • More Traits got a B42 version (some traits had to be adjusted for new systems, but it's there).
  • Many popular map mods were made B42-compatible (though note, if the map uses custom tiles and those tiles had changes in B42, you might see some oddities – but most map mods should still function).
• New Mods for B42: Interestingly, B42's new features inspired new mods:
  • Surviving Through Seasons: enhances the new farming by adding more effects of seasons.
  • Craftable Long Sticks: since stick crafting changed, a mod lets you craft them easily again.
  • Water Goes Bad: now that games can last longer, one mod makes stored water stagnate over time, adding challenge for late-game.
  • Realistic Weapons/Armor mods: e.g. an "Armored Vests" mod adds ballistic vests (for those gunfights), updated for B42.

For now, if you're on B41, enjoy the vast mod library. If you're on B42, check the Steam Workshop's Build 42 tag/collection – there are curated lists like "B42 Essential Mods Collection" containing 200+ mods that work on B42 (some of which also have B41 versions). That's a great way to quickly get the must-haves.

To close out the mod discussion, let's address one scenario: transitioning a modded server from B41 to B42 when the time comes. This will essentially be a fresh start – B41 mods won't carry over, so you'll wait until your must-haves are updated to B42, then start a new server on B42, re-subscribing to the updated mods. There's no shame in continuing a B41 server for months even after B42 stable is out, if mods lag behind. The community will likely keep two branches alive until the major mods fully migrate.

Multiplayer Workarounds in Build 42 – (If You Really Can't Wait)

We touched on this earlier, but here we'll detail the currently viable ways to enjoy Build 42 with friends before official MP returns. These are not true multiplayer in the traditional sense, but they let you cooperate in B42's world to some extent:

So, those are your options if you must play B42 with friends now. The experience won't be as smooth as true multiplayer, but it can be surprisingly enjoyable. A duo on Remote Play might treat it like an extended split-screen session. It's almost like how we'd play on a couch, but over the internet.

One creative idea: some groups have done "streamer server" where one person plays B42 and streams on Discord, and others role-play as if they're there, telling the player what to do or making decisions together. This is more for roleplay/story events – not actual interaction, but it shows how people find ways to have fun collectively even with single-player.

Alright – we've covered a huge range of topics. By now, you should feel equipped with knowledge on both versions, how to play, and what to expect.

Before we conclude, let's provide a patch history of multiplayer-relevant changes for those interested in the nitty-gritty of how PZ has evolved from B41 through B42. (Feel free to skip if you're not into changelogs – we've tucked it in a collapsible section.)

Patch History: Multiplayer Highlights

Conclusion & Checklist

Project Zomboid's journey from Build 41 to Build 42 represents a huge leap – not just in features, but in the multiplayer experience that is yet to fully unfold. Build 41 is currently the go-to for multiplayer, offering a stable and moddable platform for countless hours of co-op survival. Build 42, while single-player only for now, gives us a thrilling taste of what's to come: richer late-game, deeper collaboration mechanics, and yes – eventually – a much improved multiplayer that will feel fresh and challenging in new ways.

The community's sentiment can be summed up as eager patience. We're eager for B42's MP (who doesn't want to rebuild civilization with their friends in Kentucky?), but we're patient because we know the wait will make it better. As one community member wisely pointed out, "It's better to delay multiplayer than to release something half-baked that frustrates players." Given how far PZ has come – one of the oldest Early Access games still getting massive updates – a little more waiting for quality is a price we're willing to pay.

In the meantime, Project Zomboid Build 41 continues to offer one of the most compelling cooperative experiences in gaming. So gather your group, double-check those port forwarding rules, mod up if you like, and dive back into Knox Country. And if you venture alone into the wilds of Build 42, take notes – you'll be the one teaching your friends how to ranch cows and forge steel when the multiplayer update hits!

Stay safe out there, survivors – and remember: in multiplayer, no one has to eat their dead rat stir-fry alone. Good luck!