Installing a modpack (Modpacks)

What this is about

A modpack is a ready-made bundle of mods, configs and a mod loader (Forge, NeoForge, Fabric and so on) that turns Minecraft into a different game: All the Mods, Cobblemon, SkyFactory, RLCraft and thousands more. The Modpacks tab in the sidebar lets you search the big modpack sites and install a pack on your server with one click. The panel downloads the pack's server files and sets up the loader for you. You don't need to upload anything.

Installing a modpack replaces the server software you have now. Your old server jar, mods and libraries are removed and the pack's files take their place. Your world is kept unless you tick the "delete all files" switch, but a different pack (or even a newer version of the same pack) can corrupt a world made with another one. Take a backup first.

Where the packs come from

The dropdown at the top right picks which site to search. CurseForge is selected by default.

Type a name into Search... and the list updates as you type. Results come in pages of 40; use the page numbers to go further. Each card shows the pack's icon and name. Click a card to see its description and versions.

Can't find a pack? Check the dropdown. A pack is usually only on one of the sites, so try the one its creators use. If a search returns no results at all on every site, the site may be down or slow; try again in a minute.

Installing a modpack

1. Stop your server (Console tab) and tell your players. Installing stops the server anyway, but a clean stop saves your world properly first.
2. Make a backup on the Backups tab, especially if you already have a world you care about.
3. Open the Modpacks tab, pick the source, search for the pack and click its card.
4. In the Install … window:
   • View modpack on CurseForge (or whichever site) opens the pack's page in a new tab, where you can read the requirements and the recommended amount of RAM.
   • The version dropdown lists every release of the pack, newest first. The newest one is pre-selected. Pick the version your players will be using. The server and every player's client must run the same pack version.
   • "Do you want to delete all files of this server before performing this action?": leave it off to keep your world, server.properties, whitelist and ops. Switch it on for a completely fresh server. This deletes everything, including your world, and can't be undone.
5. Click the red Install button. Cancel closes the window without changing anything.

After you click Install the panel takes you to the Console. The server shows Installing with a progress bar, and you can't start it until the install is done. Big packs download hundreds of mods, so this can take several minutes. When the console says Installation has completed successfully. you're ready to go. If you need to abort, the Cancel button next to the progress bar stops the install.

What installing actually does

It helps to know what happens behind the scenes:

• Your server is stopped if it's running (it's force-stopped after 30 seconds if it doesn't react).
• If you ticked the "delete all files" switch, the whole server folder is emptied first.
• The old server jar, the mods, coremods and libraries folders and the Fabric/Forge launcher files are removed. Everything else (your world, configs, server.properties, whitelist.json, ops.json, backups) stays.
• The pack's server files are downloaded from the site you chose and put in place, together with the mod loader the pack needs.
• Your server type (egg) and your Startup settings stay as they are. After the install finishes, the panel looks up which Java version the pack's Minecraft version needs and switches the Docker Image on the Startup tab to it, so you don't have to.

Because your world and your settings stay, installing a newer version of the same pack is the normal way to update it. The card at the top of the Modpacks tab reminds you which pack you installed last, and when; click it to jump straight to its version list.

Changing to a different pack on top of an existing world almost always breaks the world, because the mods that created its blocks and items are gone. For a new pack, either turn on the "delete all files" switch, or restore a backup from before you installed the first pack.

Starting it for the first time

1. Go to the Console tab and click Start.
2. If this is a fresh server, the panel asks you to accept the Minecraft EULA. Accept it and the server starts.
3. The first start of a modpack is slow (often 2 to 5 minutes, longer for huge packs) because every mod sets itself up and the world is generated. Watch the console. It's done when you see Done (…s)! For help, type "help".

If the server stops with an out-of-memory error, or crashes before "Done", see How much RAM does a modpack need? below.

Your players need the same modpack

A modded server only accepts players who run the same mods. Each player installs the pack on their own computer with the launcher that matches the site you installed from:

Make sure everyone picks the same version of the pack you chose in the install window. Then they add your server's address from the Network tab in Multiplayer as usual. A player with the wrong version or missing mods gets a "mod rejections" or "incompatible" message when they try to join.

How much RAM does a modpack need?

Modpacks are much hungrier than a plain server. As a rule of thumb:

Most pack pages state a recommended amount; your server needs at least that. Your server uses the memory of your plan automatically (the startup command lets Java take up to 80% of it, and the rest is needed by the system), so there's nothing to tune in the panel. If the pack needs more than your plan has, upgrade it on the billing site, see Upgrade/Downgrading Servers. Your files and world stay as they are.

Going back to a normal server

Modpacks don't have an "uninstall" button. You have three ways back:

• Restore a backup from before the install. On the Backups tab, restore it with both options turned on (delete all files first, and restore the startup settings). That gives you the server exactly as it was, including the old Java image. See Backups: create, restore and download.
• Reinstall a plain server. On the Settings tab, use Reinstall Server with the "delete all files" switch on. The panel installs the plain server type you had before the pack (for example Paper), with a fresh world. Check the Docker Image on the Startup tab afterwards: a new Minecraft version needs the newest Java, and the modpack may have switched it to an older one.
• Switch to a different pack or server type. Install another modpack with the "delete all files" switch on, or use the Versions tab to install a plain Vanilla/Paper/Fabric jar. Remove the leftover mods and config folders yourself in the file manager if you keep the old files.

Common problems

If you're stuck, open a ticket on the billing site and tell us the pack, the version and what the console shows, see Getting help: support tickets.