How to Install a Modpack on a Server (ATM, Create)

The easiest way to install a modpack on a Minecraft server is the in-panel installer: you pick a pack from CurseForge or FTB, choose a version, and the panel downloads the server build of the pack, sets up the right loader and unpacks the mods for you. Doing it manually is the same process — you just upload the Server Pack, the Forge/Fabric/NeoForge installer and the configs over SFTP yourself. Below we walk through both methods and the mistakes that trip people up.

Server-side vs client-side modpack — what's the difference

The thing that confuses newcomers most: "the modpack on the server" and "the modpack in your launcher" are not the same thing. A pack is made of three kinds of mods: server-side (world generation, mobs, mechanics), client-side (minimaps, shaders, interface tweaks) and shared ones that belong on both. The server gets the Server Pack — a trimmed version of the pack with the purely visual mods stripped out. So installing a modpack on the server and installing the same pack in the launcher are two separate steps, and you need to do both.

The key rule: versions must match. The server and every player must use the exact same set of gameplay mods, the same loader and the same Minecraft version. If the server is on All the Mods 10 version 2.40 and a player is on 2.38, they simply won't get in — they'll hit a mod-mismatch error. So as soon as you pick a pack, lock down the version and share it with your players.

Tip

If a pack is made up of client-side mods only (optimization, shaders, minimaps), there's nothing to put on the server — just spin up a regular Paper or Vanilla core, and the mods stay local to each player.

Method 1: install a modpack in one click from the panel

This is the recommended route for beginners and seasoned admins alike — the panel picks the loader and Java for you, so there's almost nothing to get wrong. On Elysium the installer is built into the Pterodactyl panel and works with the CurseForge and FTB catalogs. Here's the step-by-step.

Open the server control panel. Log in to your Elysium dashboard and open the Pterodactyl panel for the server you need. If a server is already running, stop it with the Stop button before changing packs, just to be safe.
Pick a modpack in the installer. Go to the pack installer, choose CurseForge or FTB as the source and find the modpack you want — for example All the Mods 10 or Create: Astral. You can paste a link to the pack page or its ID.
Choose the pack version. Select a specific version of the modpack. Note it down and tell your players — their client must run exactly the same version, or they won't be able to connect.
Confirm the install and wait for it to unpack. Start the install. The panel downloads the Server Pack, sets up the right loader (Forge, Fabric or NeoForge) and unpacks the mods and configs for you. This usually takes from one to a few minutes.
Check RAM and Java version. Make sure the server has enough memory for the chosen pack and the correct Java image (17 for older versions, 21 for 1.21.x). If resources fall short, upgrade to Nexus or higher.
Start the server and connect. Hit Start and wait for the line Done in the console — the first launch of a heavy pack takes longer than usual. Then join with the same modpack at the same version and check that the world loads without errors.

The whole point of this approach is to skip the manual fuss with installers and startup scripts. If you'd rather build a server around a specific pack from the start, the simplest option is to place an order on /order: you pick the plan, core and modpack right in the configurator, and the server arrives with the pack already installed.

Method 2: install a modpack manually over SFTP

The manual route is what you need when the pack isn't in the installer's catalog, when it's self-built, or when you're migrating a ready server from another host. The principle is the same everywhere; only the loader changes.

Step 1. Download the Server Pack specifically

On the pack's CurseForge page or the FTB site, look for the file marked Server Pack or "Server Files". Not the client archive — that won't run as a server. Inside you'll find a mods folder, the configs and, as a rule, a startup script.

Step 2. Install the matching loader version

The pack needs the same loader version as the one listed for the pack. Run the installer in server mode:

# Forge
java -jar forge-1.20.1-47.x.x-installer.jar --installServer

# NeoForge (1.20.2+, modern packs like ATM10)
java -jar neoforge-21.1.x-installer.jar --install-server

# Fabric
java -jar fabric-installer.jar server -mcversion 1.21.1 -downloadMinecraft

Not sure which loader your pack uses? It's almost always stated on the modpack page. If you're choosing a loader for your own server from scratch, our breakdown of whether to pick Forge or Fabric (and where NeoForge fits in) will help.

Step 3. Upload the files over SFTP

Connect to the server over SFTP (credentials are in the panel) and upload the mods folder, the config and defaultconfigs folders, and the server jar from the Server Pack to the server root. This is the slowest stage — the mods folder can weigh close to a gigabyte.

Step 4. Accept the EULA and set your parameters

Open (or create) eula.txt and agree to Mojang's license:

eula=true

Basic fine-tuning lives in server.properties — the port, view-distance, online-mode and the rest. What each setting does is laid out in detail in our server.properties breakdown.

Step 5. Set the startup command

In the server settings, set the launch command with the right jar and amount of memory. For mods, sensible JVM flags matter — the standard here is Aikar's flags, which cut garbage-collector (GC) pauses on large amounts of RAM:

java -Xms8G -Xmx8G -XX:+UseG1GC -XX:+ParallelRefProcEnabled \
  -XX:MaxGCPauseMillis=200 -XX:+UnlockExperimentalVMOptions \
  -jar server.jar nogui

This is a shortened version; we put together the full flag string and an explanation of every parameter in our guide on Aikar's flags and JVM tuning. On Elysium the startup script and Java are filled in automatically, so when you install from the panel you can skip this step.

How much RAM and which loader a modpack needs

Memory is the main resource for mods. A rough guide to how heavy a pack is:

Pack type	Examples	Mods	Server RAM	Elysium plan
Light	Create (minimal), small tech packs	50-150	4-6 GB	Common / Pulse
Mid-sized	Create packs, Better MC	150-300	6-8 GB	Pulse / Nexus
Heavy "all-in-one"	All the Mods 10, large FTB packs	400-500+	10-16 GB	Apex / Titan

The numbers are approximate and depend on your player count: every active player loads their own chunks and adds load. For a precise estimate by mod count and players, see the guide on how much RAM a server needs. As for the loader, the rule of thumb is simple: most recent big packs (including ATM10) have moved to NeoForge for versions 1.20.2 and up, classic packs stay on Forge, and light optimized packs often run on Fabric.

A note on hardware

A modded server is bottlenecked not only by RAM but by a single CPU core — Minecraft parallelizes poorly, and the world ticks on one thread. That's why high clock speed is critical for heavy packs: on Elysium that means a Ryzen 9 boosting above 5 GHz, real DDR5 with no overselling and NVMe Gen4, so chunk loading doesn't drag down your TPS.

Common mistakes when installing a modpack

Too little RAM. The most common cause of crashes. The server dies with an OutOfMemoryError or lags hard under load. Fixed by raising memory and the plan.
Wrong Java version. A 1.21.x pack on Java 17 simply won't start. Recent packs need Java 21, older ones need 17. In the panel the Java image is a one-click switch.
Client-side mods on the server. Shaders and minimaps aren't needed on the server and sometimes crash the launch — their place is in the client only.
Mismatched versions between server and players. A pack-version or loader mismatch and the connection drops with a "mod rejected" error. Keep everyone on the same version.
Mixed loaders. Forge mods don't run on Fabric, and vice versa. Every mod must be for one loader and one Minecraft version.

If the server is already set up but lags, the cause is almost always somewhere on this short list — we cover diagnostics separately in why a server lags and how to fix it.

Popular packs and how demanding they are

To size up a plan in advance, keep each pack's reputation in mind:

All the Mods 10 (ATM10) — an "all-in-one" pack of roughly 500 mods, running on NeoForge for 1.21.1 and requiring Java 21. The hungriest category: 12-16 GB for a group, on the Apex or Titan plans.
Create packs (Create: Astral, Create: Above and Beyond) — built around the Create mechanic. Moderate load, but lots of moving contraptions hammer that single CPU core; 6-8 GB, on Pulse or Nexus.
Better MC — a big adventure pack focused on content and atmosphere. Heavier than average because of the sheer amount of world generation; plan for 8 GB and up.

If you're planning a genuinely heavy modpack, start with the Nexus (8 GB) plan or higher — a serious pack will choke on 4 GB. Which host can handle packs like these at all and what to look for when choosing is covered in our piece on the best hosting for modpacks. And you can build a server around a specific pack right in the configurator — the modpack is installed in one click when you order.

Frequently asked questions

Can I run any modpack from CurseForge on a server?

Almost any one, as long as the pack ships a server build (Server Pack). Most popular packs — All the Mods, Create, Better MC — publish one. Packs built entirely from client-side mods (shaders, minimaps, interface add-ons) have no server side, so there's nothing to install on the server; you can run a plain vanilla core and the mods stay local to each player.

Do players need the same modpack that's on the server?

Yes, and exactly the same version. The server and the client must share the same set of gameplay mods and the same loader (Forge, Fabric or NeoForge) on the same Minecraft version. If the versions drift apart, you'll hit an error like "mod rejected" or get dropped while connecting. The easiest fix is to hand players a link to the same pack in the CurseForge or Modrinth launcher.

How much RAM does a modpack need?

Light packs of 50-100 mods run comfortably on 4-6 GB. Mid-sized ones (Create, ~150-250 mods) want 6-8 GB. Heavy "all-in-one" packs like All the Mods 10 (around 500 mods) need 10-16 GB for a small group. For a detailed estimate by mod count and player numbers, see our guide on server RAM.

Which Java version does a modpack need?

It depends on the Minecraft version. Packs on 1.20.4 and below usually run on Java 17, while recent packs on 1.21.x (for example ATM10 on NeoForge) require Java 21. Pick the wrong version and the server won't start — it throws an incompatibility error. In the Pterodactyl panel the right Java is a single image toggle.

Why does a modded server take so long to start?

That's normal. A heavy pack loads hundreds of mods and builds and caches the item and recipe registries — the first launch can take 2-5 minutes or more. Don't restart the server until the line "Done" appears in the console. If startup keeps timing out, the usual culprit is too little RAM or the wrong Java version.

Can I switch modpacks without losing my world?

Sometimes, but be careful. Moving to a newer version of the same pack is usually safe. Swapping the whole pack almost always breaks the world: removed mods take their blocks and items with them, leaving holes wherever they once generated. Make a backup before any update — on Elysium plans backups are created automatically, so you can roll back in a couple of clicks.

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