How to install a modpack on your server

Before you install

• Check the memory. Big packs need a lot. When you pick a pack the panel shows what the makers recommend next to what your server has. How much RAM a Minecraft server needs has the rule of thumb.
• Make a backup in the Backups tab if there is a world on the server you want to keep. A modpack usually comes with its own world settings, and modded worlds cannot be opened without the mods.
• Agree on the pack and version with your friends first. Everyone must use the same one.

Install a CurseForge or FTB pack

1. Open the Mods tab and go to CurseForge and FTB packs.
2. Search for the pack by name, for example All The Mods, Better MC or Cobblemon.
3. Pick the version you want. Choosing a version also sets the right loader and Minecraft version on your server.
4. Click Install this pack. The panel stops the server, downloads the pack's server files and installs them. Leave the page open; a big pack takes a few minutes.
5. When it says the pack is installed, start the server from the Console. The first start of a modpack is slow, often several minutes, while every mod sets itself up.

A pack only appears if its makers published a server version. Packs that are meant for singleplayer only do not show up, which saves you from installing something that cannot run on a server.

Get your players into the same pack

Unlike plugins, mods run on both sides. Every player needs the same pack at the same version in their own launcher.

1. Players install the CurseForge app, the FTB app, Prism Launcher or Modrinth, depending on where the pack lives.
2. They search the same pack and install exactly the same version as the server.
3. They start the game from that profile and join with the server address.

Join a modded Minecraft server is a page you can send to your players, with the errors they are most likely to see.

Add single mods

You can also build your own set. In the Mods tab, search for a mod and install it: it lands in the mods folder, matched to your loader and Minecraft version. Restart to load it.

• Many mods need a library mod, such as Fabric API or Architectury. If the server stops at startup, the error names the missing one.
• Some mods are client only, such as minimaps or shader loaders. They do not belong on the server and can stop it from starting.
• Adding mods to a finished modpack is possible, but players must add the same ones.

Updating a pack

Pack updates can change world generation or remove items. Read the changelog, make a backup, install the new version in the Mods tab, and tell your players to update at the same moment. A player on the old version cannot join the new one.

When the server does not start

• A client only mod: the log names a mod and mentions a missing client class. Delete that mod from mods.
• Out of memory: the log shows OutOfMemoryError. The pack needs more RAM than the server has.
• Wrong Java: modern packs need a recent Java. Changing the Minecraft version in Settings sets the matching Java by itself; see which Java version your server needs.