Project Zomboid Build 42.21 Moves from Unstable Beta to Stable

Build 42.21 spent time in Project Zomboid's Unstable beta branch before the developers pressed the release button for Stable on September 28, 2026. The community reported no major issues during that window — a process the studio describes as the intended standard procedure for future releases.

What changed

• Zombie duplication (MP) and disappearance (SP/MP): The worst-offending bugs causing zombies to duplicate in multiplayer, or vanish when a player left and re-entered a world chunk, have been addressed. The studio notes the problem was most visible in high-population games and affected hardcore players disproportionately. Some edge cases remain and are targeted for the next update.
• XXL tree rendering: The oversized trees introduced in Build 42 Stable drew consistent complaints, particularly around driving. Trees now cut away more reliably when a player is in a vehicle, no longer obscure houses and furniture they overhang, and have adjusted transparency for better visibility overall. The studio flags this as a work in progress.
• Lua loadstring / loadstream re-enabled: These methods were disabled in 42.20.4 to address a security vulnerability. After further investigation, the developers reversed course and restored them, acknowledging the disruption to modders and server administrators.

Full patch notes are available on the Indie Stone forums. For players running larger zombie populations or heavily modded servers, 42.21 represents a meaningful stabilization — with the developers signalling that further refinements on trees and zombie behavior are already queued.