Installation

Installation

Requirements

Minecraft	1.21.11
Fabric Loader	≥ 0.19.3
Fabric API	required
Java	21 or newer

Steps

1. Install Fabric Loader for Minecraft 1.21.11.
2. Drop Fabric API into .minecraft/mods/.
3. Drop the mcMMO jar from the Releases page into .minecraft/mods/.
4. Launch the game. Configs are generated on first world load.

That's it. mcMMO has no other hard dependencies, and nothing needs configuring before you play.

Optionally add Mod Menu + Cloth Config for an in-game settings screen, and Advancement Plaques for fancier milestone popups — see Optional Integrations. None of them are bundled and none are required.

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Where things go

Configuration — global, one copy

.minecraft/config/mcmmo/

Written on first load. See Configuration for what each file controls.

Save data — per world

<world save>/mcmmo/players/

Skill data is stored per world, not globally. Each player gets their own flat file.

This has consequences worth knowing:

• Copying a world copies its skills. Backing up a world backs up your progression.
• Deleting the mcmmo folder resets progression for that world only. Other worlds are untouched.
• A new world starts you at zero. There is no global profile.

The same folder also holds placed_blocks.dat, the anti-exploit record of blocks you placed yourself (so you can't farm XP by placing and re-breaking the same block, across restarts).

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Single-player, LAN and servers

The mod declares "environment": "*" and runs on both sides, so it works in single-player, on an opened-to-LAN world, and on a dedicated Fabric server.

But the multiplayer feature set was removed during the port, not merely disabled — no parties, no party chat or teleport, no XP sharing, no scoreboards, no admin broadcast tree, no MySQL. On a server, mcMMO-SP is simply "everyone has their own skills, independently."

If you want the full multiplayer experience, use upstream mcMMO on a Paper/Spigot server instead. That is what it is for.

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Upgrading

Replace the jar. Config files are not overwritten.

⚠️ Editing defaults in the jar does not update an existing config. On load, mcMMO back-fills keys that are absent from your config file, but keys already present on disk are left exactly as they are — including ones you never touched. So if a new release changes a default, your existing config keeps the old value silently.

To pick up a changed default, delete the key (or the whole file) and let it regenerate.

If a skill was renamed between releases, mcMMO logs a warning naming the old and new config section rather than rewriting your file for you. Your config is yours; a silent rewriter is a worse failure mode than a log line.