Add-ons: behavior and resource packs

Two kinds of add-on

• Behavior packs: change mobs, items and game rules. They run on the server, and players download nothing.
• Resource packs: change textures and sounds. Players are offered the download when they join.

A player can decline the resource pack download and still join, without its textures and sounds. To make it required, turn on Require the resource pack in Settings, under Access and chat. A player who declines is then disconnected.

Installing one

You have two routes, and both end up in the same place:

1. Add-on catalog: find an add-on and install it with one click.
2. Upload an add-on: if you already have a .mcaddon or .mcpack file, upload it from the same tab.

Install with your server stopped, because an add-on can't go in while the game runs. We install the add-on and activate it on your world, and you start the server again afterwards.

What the catalog installs

The catalog installs the add-on's newest file made for your server's Minecraft version, or its newest file when none is marked for that version. Some authors publish the behavior pack and the resource pack as two separate files. When the chosen file needs a pack it doesn't include, we look through the project's other recent files, those for the same Minecraft version first, download up to four of them, and install the file that holds the missing pack along with the chosen one.

If a required pack is still missing after that, the install stops and names the add-on that needs it. Install the missing pack first, from the catalog or as an upload, then install the add-on again.

Some authors allow downloads only from CurseForge itself. The catalog then tells you to open the add-on's page, download the file there, and upload it with Upload an add-on.

Order matters

If several resource packs change the same thing, the order decides which one wins. You can move them up and down in the list.

Requirements and shared worlds

The installed list includes discovered packs from the active world and server folders. It shows which worlds use each pack and its declared dependencies, including Script API modules. These declarations help diagnose compatibility, but they don't prove that a script loaded successfully.

Installing or enabling a pack checks that every pack it requires is installed at the declared version or newer, and checks its declared minimum Minecraft version. Required packs are activated first. Missing dependencies and dependency cycles stop activation. Disable dependent add-ons before disabling a pack they need.

A pack used by another world can't be removed or switched to a different version until those references are removed. This prevents fixing one world from breaking another. Pack changes need a stopped server, and only removing a pack takes a backup first. If an install fails, the previous files come back.

After restarting, open the console and look for content errors. "Installed · load unverified" means the files are present. It doesn't mean the game loaded the add-on.

Add-on check and repair

The Add-on check on the Add-ons tab looks for four problems:

• Add-on files uploaded through Files straight into behavior_packs or resource_packs. The game never opens an archive, so these never load.
• Packs whose folders are on the server but were never activated on the world.
• Required packs that are missing, such as a behavior pack whose resource pack was never installed.
• Add-ons that need Beta APIs.

Repair add-ons fixes the first two and the last one. We take a backup and stop the game, activate the packs that were never activated, install every add-on file through the same installer an upload uses, turn on Beta APIs when an installed add-on needs it, and start the server again if it was running. A file we can't install stays where it was, and the console says why. A zip that holds no add-on at all is listed as not an add-on and left alone.

Beta APIs

Some add-ons use Minecraft's beta scripting, and their scripts only load when the Beta APIs experiment is on for the world. The installed list marks them as "Needs Beta APIs".

Repair add-ons turns it on for the active world when an installed add-on needs it. Once it's on, it can't be turned off safely, so the backup taken before the repair is your way back.

If we can't read the world's settings file, the check says so, and you can turn it on from your device instead:

1. Open the world on your device.
2. Go to Settings → Experiments and turn on Beta APIs.
3. Export the world as a .mcworld file.
4. Upload it from the Worlds tab and activate it.