Our team has been working on the Project Zomboid multiplayer layer continuously since the Build 42 MP rollout in December, and with 42.20.0 that work has gone to the public Stable branch — after four and a half years of unstable builds, Build 42 is now simply Project Zomboid. The multiplayer section is by far the longest in this changelog at 111 entries, 99 of them fixes, and most of our work this cycle is reflected there. Across the seven builds since February, 42.14 through 42.20, those sections total 453 entries and 384 fixes.
The largest single piece is the anti-cheat rework we began in 42.18 and have now completed. We re-enabled the anti-cheats, moved antiCheatItem to the server side so the client is no longer trusted with it, and rebuilt the logging around them so that a trigger can actually be diagnosed rather than guessed at. NoClip and PacketException remain work in progress, and we would rather say so than call them done. We also closed another set of exploits — item spawning through modData and through animal attachment commands, item manipulation while foraging, illegitimate XP gain, and a map exploit that let a client copy dedicated-server map data — and cleared a batch of anti-cheat false positives along with them.
The rest of our cycle went into throughput and desync, and it should be visible to anyone running or playing on a server. We reworked the transfer of stackable items so that large stacks move in a fraction of the time, cut the wait between pressing "Click to Start" and spawning into the world, and improved network performance during vehicle collisions with zombies. We fixed a culling bug that was quietly thinning zombie populations on live servers, chunks failing to load while driving, cells within a chunk never loading for some clients, a server hang during chunk generation, and the stutter every player felt whenever someone interacted with a gate. Remote players no longer land instantly while falling, freeze while moving crouched, vault fences they are only walking past, or drop corpses they are still dragging — and killed zombies no longer duplicate after a relog. For server administrators we added per-player ping in the Players and Users lists, a "Show coordinates" server option, more consistent and configurable ZNet logging, more reliable packet logging, and object pool statistics for live monitoring.
We could not have asked for a harder test of that work. Project Zomboid's all-time concurrent record of 65,505, which had stood since January 2022, fell within hours of the stable release and kept climbing for days, peaking above 120,000 — almost double a record that held for four and a half years. We want to thank The Indie Stone for the partnership and for holding Build 42 back until it was ready, and the community that ran the unstable branch alongside us all year: the server administrators who sent us logs, saves and step-by-step reproductions, the bug forum reporters, the Discord regulars, and the community translators. A very large share of those 384 fixes began as somebody's carefully written report. We continue to iterate with The Indie Stone through the hotfixes, the late-game tuning patch and the Build 42 Support Update running across the rest of 2026 — multiplayer work continues, and we would ask you to keep the reports coming.