Project Zomboid Build 42.21 Hits Stable Branch

From Unstable to Stable

Project Zomboid's development team has promoted Build 42.21 from the Unstable beta branch to Stable. The update spent time in testing with the community before release, following the project's current workflow: new builds first go to Unstable, players test them, the developers make any necessary adjustments, and the build is then pushed to Stable once no major issues are reported. In this case, testers did not flag any serious problems, clearing the way for today's release.

Zombie Duplication and Disappearance Fixes

The headline change in 42.21 addresses some of the most disruptive bugs affecting zombie behavior in multiplayer and singleplayer games alike.

• Zombie duplication in multiplayer has been significantly reduced by fixing the underlying causes of the bug.
• Zombies disappearing after a player leaves and re-enters a loaded "chunk" of the game world has also been addressed, affecting both singleplayer and multiplayer sessions.

These issues were especially noticeable in games with larger zombie populations, making them a priority for players running high-difficulty or horde-heavy saves. While the fixes in this build represent major improvements, the development team has noted that a small number of related edge cases remain and are already being tracked for a future update.

XXL Tree Visibility Improvements

Since Build 42 Stable launched, one of the most common pieces of player feedback concerned the game's new "XXL trees" obstructing visibility and movement, particularly while driving.

Build 42.21 adjusts how these large trees behave when they overlap the player's view:

• Vehicles now trigger better tree cutaway effects, making it easier to see the road while driving.
• Trees no longer obscure houses or furniture that they overhang.
• Overall tree transparency has been tuned for improved visibility in general.

The developers describe this as a meaningful step forward rather than a final fix, with further refinements planned for future builds.

Lua Security Rollback

In the earlier 42.20.4 update, the loadstring and loadstream Lua methods were disabled as a precaution following the discovery of security vulnerabilities. After further investigation, the development team determined it was safe to re-enable both functions, restoring functionality that many modders and server administrators rely on. The team acknowledged the inconvenience this temporary disabling caused within the modding community.

What Else Changed

Beyond these headline fixes, Build 42.21 includes a broader set of smaller changes and bug fixes covering general stability and gameplay polish. Players looking for the complete, line-by-line changelog can find it in the official patch notes thread on The Indie Stone forums.

Reporting Issues

Players who encounter bugs in 42.21 are encouraged to submit reports through the official bug reporting forum, following the posting guidelines outlined there. Reports made elsewhere — including on Discord — are unlikely to be tracked or investigated by the development team, so using the proper channel remains the most effective way to help improve future builds.