Data packs on a Minecraft server: install, commands, safety

In short: put the .zip or folder with a pack.mcmeta file into world/datapacks and run minecraft:reload from the console — or restart the server. Check with datapack list enabled: the pack shows up as [file/name]. Packs that change world generation, dimensions or enchantments only apply after a restart, and world generation goes in before the world is created.

What a data pack is and how it differs from a plugin#

A data pack is a folder or .zip archive with a pack.mcmeta file at its root and a data folder. Inside are JSON definitions, .mcfunction functions (lists of commands) and .nbt structures. The game itself keeps vanilla recipes, loot and generation in a built-in vanilla data pack, which is why another pack can add to them or replace them.

What a data pack can do: recipes, advancements, loot tables, predicates, tags, functions, structures, world generation, dimensions, enchantments, mob variants, dialogs. What needs a plugin: custom commands with permissions, economy, land claims, databases, and anything that has to work on a player's network packets.

How to install a data pack on a server#

1. 1

   Download a pack for your version

   It's a .zip or a folder. Make sure pack.mcmeta sits at the root of the archive, not inside a nested folder — otherwise the game won't see the pack.

2. 2

   Put it in the world folder

   Into datapacks inside the world folder: world/datapacks by default (the world name comes from level-name in server.properties). Create the folder if it isn't there.

3. 3

   Reload or restart

   Recipes, loot, advancements and functions are picked up by minecraft:reload. World generation, dimensions, enchantments and the other "experimental" parts need a restart.

4. 4

   Check

   Run datapack list enabled in the console. If the pack isn't listed, look for the error in logs/latest.log — see logs and crashes.

If a pack has an error, such as a broken recipe format, minecraft:reload doesn't apply the changes and the game keeps running on the previous data. The datapack enable and datapack disable commands reload packs too.

The /datapack command#

Order matters: when the same file exists in several packs, the one loaded last wins, while tags without "replace": true merge. The order is stored in the world's level.dat. Packs that need an experimental feature flag can only be enabled when the world is created — the command can't turn them on later.

Packs at world creation: server.properties#

Two server.properties keys only act when a new world is created — they don't touch an existing one:

A world generation pack only affects new chunks; chunks that already exist stay as they are. So install it before the first start or before pregenerating the world, not on a lived-in server.

pack.mcmeta and the format number#

pack.mcmeta tells the game which versions a pack was made for. Since 1.21.9 a single pack_format gave way to a min_format and max_format range; the old field is only needed if the pack also supports versions from before this scheme.

{
  "pack": {
    "description": "Server recipes",
    "min_format": 94,
    "max_format": 94
  }
}

Safety: trusted sources only#

• A pack's functions are server commands. They run at the permission level from function-permission-level (2 by default) — the level that allows, for example, /gamerule, /worldborder and /datapack. A pack from a shady source can quietly change your world.
• Look inside. A data pack is plain text files: before installing, open the function folder and check which commands run, especially in functions tagged minecraft:load (on load) and minecraft:tick (every tick).
• Every-tick functions cost TPS. A heavy function in minecraft:tick loads the server constantly — measure it with a profiler: see spark.
• Back up first. A generation or dimension pack changes the world for good — make a backup.
• If the world won't load. Paper can start worlds with only the built-in vanilla pack via the --safeMode launch argument. That lets you remove a broken pack.

Data packs and the anticheat#

A data pack sees the game through data and commands, not through the client's network packets. So packet-level checks — Timer, Blink, BadPackets — can't be built from functions: an anticheat is a plugin. DGuard — the best anticheat for a modern Minecraft server — runs on Paper and Leaf 1.21–26.3 next to PacketEvents and catches cheats in combat, movement, packets, inventory, building and the world.

If a data pack changes speed, knockback or attack reach — with custom enchantments, say — check the punishment log after installing it to see whether honest players started showing up. DGuard gathers evidence without rushing to a verdict, and you set how strict it is. How to sort out disputed cases — in false bans.

FAQ#