
Hazmat
unethical bugfixes and crash "fixes". Free Minecraft Java mod for 1.21, 1.21.1.
⬇ Download on ModrinthHazmat
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.
Force Attribute
DefaultAttributeContainerMixin=false in the config to disable. Will prevent any crashes due to entities not having attributes set.
Packet Fucker
DecoderHandlerMixin=true in the config to enable. Will prevent any crashes due to invalid server-sent packets. NOT GOOD FOR GENERAL USE. This was implemented as a temporary flag to go into broken worlds to manually remove broken blocks or items.
Player Backup x7
PlayerSaveHandlerMixin=false in the config to disable. Will keep seven extra playerdata backups alongside the normal one.
- Ships as hazmat-1.2.1+1.21.1.jar — drop this file into the mods folder
- Download size: 10 KB
- Download link checked 5 Sept 2026 — working
These come from our own check of the pack file, not from the source page.