Running Fabric, Forge, NeoForge and modpacks on a Minecraft server

Mods vs. plugins and choosing a loader

Mods change the game itself (new blocks, items, dimensions) and players must have them installed in their client too. Plugins (Paper/Spigot) run only on the server — they are covered in How to install plugins.

1Back up the current server

Changing the mod loader or version is done by reinstalling, which runs the installation script and may overwrite files. Before you start, stop the server and in the Backups tab click Create Backup. If you want to keep the world, download the backup to your computer as well. Details are in Backups and version changes.

2Set the mod loader and version in the panel

You set the mod loader and game version in the panel rather than by uploading a server core by hand — the installation script downloads the right files and libraries itself.

1. Open the Startup tab. The Variables section lists the template (egg) variables — typically the Minecraft version and the mod loader version. The exact names depend on the template.
2. Enter the game version and mod loader version the modpack requires (e.g. Minecraft 1.20.1 and Forge 47.x). Variable changes are saved automatically.
3. In the same tab pick the right Java in the Docker Image field: Java 8 for 1.16.5 and older, Java 17 for 1.18 to 1.20.4, Java 21 for 1.20.5 and newer.
4. In the Settings tab click Reinstall Server and confirm. You will see the installation progress in the console.

3Upload the server pack

A server version of a modpack is usually downloaded as a separate Server Pack (on CurseForge under Files for a given version, on Modrinth in the description or project versions). If the author has not published one, build it from the client installation: copy the mods, config and possibly defaultconfigs, kubejs folders and remove client-only mods.

What to upload

The panel already installed the server core in step 2, so upload only the modpack content, not its own launch files:

/
├── mods/            ← upload (all .jar mods)
├── config/          ← upload
├── defaultconfigs/  ← upload if present
├── kubejs/          ← upload if present
├── libraries/       ← keep from the panel install
├── run.sh / start.sh / *.bat  ← not needed
└── server.properties

How to upload

• SFTP (recommended for hundreds of files): details are in Settings → SFTP Details, the password is your panel password. Connect with FileZilla or WinSCP and drag the folders into the server root.
• Archive via the panel: zip the folders, upload the archive in the Files tab with Upload and choose Unarchive from the file's menu. Delete the archive afterwards so it does not take up space.

4How much memory (RAM) a modpack needs

There is no exact number — it depends on the specific mods, world size and player count. The values below are a rough starting point for a smaller community (a handful to a few dozen players at once) and a normally sized world:

Many modpacks state recommended memory in their description — treat it as a minimum. The panel sets Java memory according to your plan; do not raise it by hand (e.g. with -Xmx in user_jvm_args.txt) above the allocated amount, otherwise the process may be killed for running out of memory. If memory is not enough, upgrade the plan in the client area.

5First start

1. Start the server with the Start button. The first start of a modded server takes longer — mods load and the world generates.
2. If the panel asks you to accept the EULA, accept it (or set eula=true in eula.txt).
3. Wait for the line:

[Server thread/INFO]: Done (42.123s)! For help, type "help"

If the server crashes, look for the cause at the end of the console or in logs/latest.log, and for crashes also in the crash-reports folder.

Connecting players: the client must match

Players need the same game version, the same mod loader and the same modpack version as the server. The easiest way is to install the modpack through a launcher that supports modpacks — e.g. the CurseForge App, Modrinth App or Prism Launcher — and pick the same modpack version the server runs.

Common errors