Hazmat
Hazmat is a Fabric utility that changes how the game handles datapack filtering and player save backups, and it bundles several crash fixes.
What it does
Hazmat targets a datapack filtering problem in the pack.mcmeta system, where namespaces were not filtered as expected, and it includes a config option to turn that fix off. It also keeps seven extra player data backups next to the normal one, which can be disabled in the config. Its crash fixes and bugfixes are described by the author as unethical in nature, so server owners should weigh them before use. Hazmat is a client or server optional mod, and it is published for Fabric only, for 1.21 and 1.21.1. Its license is custom and the mod is not open source.
Hazmat is released as Fabric files for 1.21.1, with 1.2.1+1.21.1 as the latest build, and both game versions 1.21 and 1.21.1 have files.
Key features
Datapack filter fix
Corrects the way resource packs are filtered, so namespaces are handled as the author intended, with a config switch to disable it.
Player backup retention
Keeps seven extra copies of player data alongside the normal save, with a config switch to turn the copies off.
Crash fixes
Bundles crash fixes and bugfixes, which the author labels as unethical, aimed at stopping certain crashes.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
In the catalog
Hazmat is one of 7,555 Cursed mods on ModsFinder, and one of 4,235 Cursed mods for Fabric. 32,366 mods support Minecraft 1.21.1.
More from queenofthebees
Similar mods
What the author says
Hazmat ====== Unethical "fixes" to random crash issues. Datapack Filter Fix ------------------- LifecycledResourceManagerImplMixin=false in the config to disable. Fixes Mojang's fucked up pack.mcmeta filtering system, since they somehow forgot to make the namespace filter actually do anything.
Official listing
- Modrinth page
- modrinth.com/mod/hazmat
- Owner
- queenofthebees
- Published
- 2025-03-15
- Updated on Modrinth
- 2025-04-04
- Facts verified
- 2026-10-15