How to set up a modpack server

Playing a modpack with friends is a lot easier when everyone joins one server instead of passing a world around. This guide walks you through it: finding the right files, checking the loader and version, sizing RAM, uploading the pack in the panel and getting it to start cleanly.

It's written for Shard Hosting's Pterodactyl panel, but most of it applies to any Minecraft server.

1. Find the server pack

Most modpacks come in two versions: the client pack you play with, and a server pack made for running a server. Always start with the server pack if there is one. The pack author has already removed client-only mods (like minimaps and shaders) that would stop a server from starting, and usually includes the right loader files or an installer.

Where to look:

  • CurseForge: open the modpack's page, go to its Files tab and pick the version you want. If the author made a server pack, you'll see it listed as an additional file for that version.
  • Modrinth: check the modpack's page and its version list. Some packs offer a separate server file, and some explain in the description how to set up a server.
  • The pack's own site, wiki or Discord: many larger packs keep server setup instructions there.

Download the server pack for exactly the same pack version your players will use. A version mismatch is one of the most common reasons people can't join.

No server pack? You can build one from the client pack: copy over the mods and config folders (plus any defaultconfigs or kubejs folders the pack uses), install the matching loader on the server and remove client-only mods. It's more work, so check carefully for an official server pack first.

2. Check the loader and Minecraft version

Every modpack is built on a specific mod loader and Minecraft version. You'll find both on the pack's page.

  • Loader: Forge, NeoForge or Fabric (sometimes Quilt). Mods only run on the loader they were made for.
  • Minecraft version: for example 1.20.1 or 1.21.1. The server has to match the pack exactly.
  • Loader version: many packs need a specific version of Forge or NeoForge. The server pack usually includes it.

Your server also needs a Java version that suits the Minecraft version. As a general rule: Minecraft 1.16.5 and older uses Java 8, 1.18 to 1.20.4 uses Java 17, and 1.20.5 to 1.21.x uses Java 21. Newer versions may need a newer Java. If the server fails right away with a Java version error, that's the cause.

You can set the loader and Minecraft version yourself in the panel with its version changer, and the panel's Modrinth and CurseForge browser lets you look up mods and packs without leaving it. Make a backup before you switch, because it can change your files.

On Paper, Forge and Vanilla servers, you can change the Java version yourself on the Startup page in the panel, by picking a different Docker image. On Fabric, ask us in a Discord ticket and we'll sort out the Java version for you.

3. Pick enough RAM

Modpacks need far more memory than vanilla Minecraft, and the range is wide. A light pack with a few dozen mods and a kitchen-sink pack with hundreds are very different servers.

Use our RAM calculator to get a number. Choose "Modpack", pick the pack size (or enter the exact mod count from the pack's page), set how many people play at the same time and your view distance. It suggests a RAM size and the plan that fits. If the pack's author publishes their own server requirements, the calculator uses those, and you should too.

Two tips:

  • Don't plan for the bare minimum. Modded worlds grow, and memory use grows with them.
  • Plan for the most players you expect online at once.

4. Upload and unzip the pack

Before you upload, stop the server in the panel. If there's already a world you want to keep, make a backup first.

For a small pack, use the Files page in the panel:

  1. Open the Files page.
  2. Upload the server pack's .zip file.
  3. Choose Unarchive on it to unzip it.
  4. Check where the files ended up. Many server packs unzip into their own subfolder. The mods folder, config folder and server files need to sit in the main server folder. If they're in a subfolder, move them up.
  5. Delete the .zip once it's unpacked, so it doesn't use up your storage.

For a large pack, use SFTP instead. It's more reliable for big uploads. Connect with an SFTP client like FileZilla or WinSCP using the login details shown in the panel and your panel password, then upload the unzipped files to the main folder.

Some server packs include an installer or a start script (like startserver.sh or run.sh) instead of a ready-to-run server. The panel starts your server in its own way, so you usually don't run those scripts directly. If your pack only comes with an installer, ask us in a ticket and we'll help you get the loader set up.

Finally, open eula.txt and make sure it says eula=true. That means you accept Minecraft's EULA, and the server won't start without it.

5. First start and reading console errors

Go to the Console page and press Start. The first start of a modpack is slow, sometimes several minutes, because the server loads every mod and generates the world. Wait until the console says Done.

If it stops or crashes instead, scroll up in the console and look for the first error, not the last one. Common problems:

  • Missing dependency. The console names a mod that needs another mod that isn't installed. Download that mod for the same loader and Minecraft version and add it to mods.
  • Client-only mod. Errors mentioning rendering, shaders, screens or classes like net.minecraft.client usually mean a client-only mod is on the server. Remove it.
  • Wrong loader or version. A mod built for Fabric on a Forge server, or for a different Minecraft version, fails to load. Get the right version of that mod.
  • Out of memory. Errors like OutOfMemoryError or the server stopping without a clear message under load mean it needs more RAM. Check the memory graph in the panel, then lower your view distance or ask us in a Discord ticket to move to a bigger plan.
  • Wrong Java version. Errors about an unsupported class version mean the server is running a Java version that doesn't match the Minecraft version. On Paper, Forge and Vanilla, pick the right Java version from the Docker image options on the Startup page. On Fabric, ask us in a ticket.

Crash reports are saved in the crash-reports folder, and the full log is in logs/latest.log. Both are on the Files page. If you get stuck, open a Discord ticket and attach the log. Don't paste passwords or private links in public channels.

6. Players install the same pack

To join a modded server, every player needs the same modpack at the same version installed in their own game. The easiest way is a launcher that installs packs for you, such as the CurseForge app, the Modrinth app or Prism Launcher.

Then they launch the modpack, go to Multiplayer, then Add Server, and paste your server's address from the Console page in the panel. Our joining guide covers this step in more detail.

When you update the pack later, update the server and tell your players to update too. Make a backup before every update, in case a new version breaks your world.

Next steps

Once your pack is running, our backups and schedules guide shows how to protect your world, and the lag guide helps if things slow down. Still choosing a server? See modded Minecraft hosting or the plans.