Project Zomboid build 42.20 to move to stable this summer

The Indie Stone announced that build 42.20 of Project Zomboid will move from the unstable branch to the stable branch and become the default Steam launch option, with a target window of later this summer. The studio said the update is currently in testing and described it as “a big one.”

Build 42 has been receiving regular changes on the unstable branch for 19 months. Those updates include adjustments to ranged combat and skill progression, the reintroduction of multiplayer, and other gameplay tweaks introduced across 19 major unstable iterations. The studio identified 42.20 as the candidate to bring those changes to the wider player base.

The team warned that saves from build 42.19 will not be compatible with 42.20. Players who want to keep their current saves can move to an “outdatedunstable” branch. The developer added that unstable users “have at least a few weeks” on the current version while testing finishes.

The update addresses a list of technical and gameplay issues discovered during the unstable period. The studio highlighted fixes and improvements for character spawns, controller support, meat yield from butcher hooks, vehicle towing, zombie culling in multiplayer, and map chunk loading when driving in multiplayer, among other items.

Once 42.20 reaches the stable branch, the studio plans to issue immediate hotfixes for any pressing problems and then follow with a patch focused on late-game tweaks and adjustments based on player feedback. Opening the build to the stable audience will allow the team to collect data from longer playthroughs and a broader range of hardware and server setups.

The Indie Stone also intends to release updated tools to the community, including mapping tools, an in-house animation editor, and an integration tool. The studio wrote that greater control of animations should help modders expand their work and invited contributors to assist with community-driven localization and other efforts.

For the rest of 2026, the studio outlined a build 42 support update that will focus on optimization, expanded modding support, and several player-requested features and polish that missed the stable cutoff. The update will address technical debt and aim to improve the studio’s development pipeline ahead of future major builds.

Players and server operators are advised to back up important saves and mods, test on the outdatedunstable branch if they need to preserve progress, and monitor the developer’s channels for the final release window and any post-launch hotfixes.