# Project Zomboid 42.20.1 STABLE Hotfix Released

- Product: Project Zomboid (https://whatsnew.fyi/product/project-zomboid)
- Vendor: The Indie Stone
- Date: 2026-08-05
- Original notes: https://store.steampowered.com/news/app/108600/view/676254354515165254
- Permalink: https://whatsnew.fyi/product/project-zomboid/releases/2026-08-05-42.20.1-stable-hotfix-released

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

---

- **changed** — Improved Lua checksum validation for multiplayer anti-cheat
- **fixed** — Fixed an issue that caused significant performance problems with chunk unloading on multiplayer servers
- **fixed** — Fixed errors and crashes that could occur when selecting Multiplayer while certain languages were selected
- **fixed** — Fixed an issue where vehicles could temporarily disappear for players after another player disconnected
- **fixed** — Fixed an issue that would allow broken B41 worlds to be hosted on B42 servers
- **fixed** — Fixed an issue where players switching from b41 to B42 could be met with a missing menu
- **changed** — Improved memory usage by reusing discarded world data
- **fixed** — Fixed a memory leak that could lead to performance degradation and crashes over time
- **fixed** — Fixed a rare exception that could occur during exploration
- **added** — Added the ability for mods to write .json files
- **fixed** — Fixed percent symbol handling in translation files

While this update should not break saves, if you encounter any bugs please ensure you can replicate them on a fresh save with no mods installed before reporting them to our team (https://theindiestone.com/forums/forum/85-bug-reports/).

##### MP

- Improved Lua checksum validation for multiplayer anti-cheat

- Fixed an issue that caused significant performance problems with chunk unloading on multiplayer servers

- This should fix most of the bugs players were getting on high-pop servers due to server lag

- Fixed errors and crashes that could occur when selecting Multiplayer while certain languages were selected

- Fixed an issue where vehicles could temporarily disappear for players after another player disconnected

- Fixed an issue that would allow broken B41 worlds to be hosted on B42 servers

- Fixed an issue where players switching from b41 to B42 could be met with a missing menu

##### FIXES

- Improved memory usage by reusing discarded world data

- Fixed a memory leak that could lead to performance degradation and crashes over time

- If you continue to encounter an out of memory error in a new save, please submit a bug report with your logs and profiler video from debug so the team can investigate

- Fixed a rare exception that could occur during exploration

##### TECHNICAL/DEBUG

- Added the ability for mods to write .json files

- Fixed percent symbol handling in translation files

- Mod translations should use %% to display % characters

_As always, discussions regarding this update can be found pinned to the Project Zomboid Discussions Forums (https://steamcommunity.com/app/108600/discussions/0/585056462065148405/)_.