Setting up a modpack server: Forge, NeoForge and Fabric

A plain Minecraft server runs on just about anything. But once you want to host a modpack — with dozens or sometimes hundreds of mods loading at once — there's more to it: mod loaders, RAM limits, server packs and the occasional crash you'll have to dissect yourself. It sounds scarier than it is. With a little preparation, you'll have a running modpack server your friends can join in a single evening.

We'll walk through the key decisions: which loader you need, how to pick a pack that suits your group, how much memory is realistic, and what to do when the server dies right after starting up.

Forge, NeoForge or Fabric: what's the difference?

Mods don't run on a standard server. They need a mod loader: a modified server version that can load mods and make them work together. There are three big names:

• Forge is the oldest and best-known loader. By far most classic modpacks are built on it, and for older Minecraft versions it's often the only serious option.
• NeoForge is a fork of Forge, started by a large part of the original team. For recent Minecraft versions, many big packs and mods now choose NeoForge, making it the modern successor to Forge in practice.
• Fabric is a lightweight loader that supports new Minecraft versions quickly. Popular for performance mods and for smaller, snappy packs.

Important to know: mods are not interchangeable between loaders. A Forge mod won't work on Fabric and vice versa. And to be honest: in practice you rarely pick the loader yourself. You pick a modpack, and that pack determines which loader and which Minecraft version you run. The loader question only really matters when you assemble a pack yourself — then your loader choice determines which pool of mods you can draw from.

Choosing a modpack that fits your group

Bigger isn't automatically better. A kitchen-sink pack with hundreds of mods is fun for seeing everything once, but it demands lots of memory, loads slowly and overwhelms players who are just having a look. First think about what your group actually wants:

• Tech or magic packs with a clear theme and quest lines are often better balanced and considerably lighter than everything-and-the-kitchen-sink packs.
• Skyblock and expert packs provide plenty of structure and hundreds of hours of content, but are tough for casual players.
• Light adventure or performance packs are ideal if your friends have older PCs. Remember that every player also has to run the pack on their own computer.

When choosing, check right away whether the pack offers official server files, also known as a server pack. Most big packs on CurseForge and Modrinth have them. You can manage without one, but then you have to fish the client-only mods out of the mods folder yourself — and that's exactly the kind of hassle you don't want on a Friday evening.

How much RAM does your modpack server need?

The hard truth: modpacks eat memory. Where a vanilla server with a handful of players needs little, an average modpack quickly wants several gigabytes. A rough guideline:

• Light packs (a few dozen mods): count on about 4 GB.
• Medium packs (roughly 100 to 200 mods): 6 to 8 GB is comfortable.
• Heavy kitchen-sink packs: 8 to 12 GB, especially with more than a handful of players.

More players, a bigger world and a high view distance push usage up further. Also always check the pack's own page: many creators list a recommended amount of server RAM, and that estimate is usually more reliable than a general rule of thumb.

One nuance that's often forgotten: more RAM isn't always better. Java cleans up its memory via garbage collection, and with an unnecessarily large allocation those cleanup passes can actually cause longer stutters. Give your server what the pack asks for plus some headroom, and leave it at that.

From server pack to friends playing

Installing the server pack

A modpack really consists of two parts: the client pack (what players install in their launcher) and the server pack (what runs on the server). They're not identical — the server pack, for instance, lacks shaders and other client-only mods. So never blindly put the client pack on your server. The route looks like this:

1. Download the pack's server files via CurseForge or Modrinth.
2. Upload them to your server, or use the modpack installer in your control panel if your host offers one — that saves a lot of file shuffling.
3. Accept the EULA by setting the value in eula.txt to true.
4. Start the server and be patient: the first start of a big pack can take quite a few minutes, because all mods have to create their registrations and config files.

If the server crashes immediately on startup, first check whether any client-only mods accidentally ended up in the mods folder. A mod that only does something graphical will take a server down without mercy.

Everyone on the same mods: keeping clients in sync

The most common frustration with modpack servers isn't the server itself, but players who can't get on it. The rule is simple: everyone runs exactly the same pack in exactly the same version. If a single mod version differs, you'll be rejected when joining or miss content in the world.

• Have everyone install the pack through a launcher with modpack support (like the CurseForge app, the Modrinth app or Prism Launcher) and agree on one version number.
• Turn off automatic pack updates. Nothing is as annoying as a player whose launcher has quietly jumped to a newer version.
• Update the server first, and only then ask everyone to update — never the other way around.
• Client-only mods like minimaps and shaders are fine for players to add themselves; those don't need to be on the server.

Server crashing? Here's how to find the culprit

Sooner or later it happens: the server no longer starts or drops out mid-game. Don't panic — modded Minecraft tells you surprisingly precisely what went wrong, if you know where to look.

• Crash reports: in the crash-reports folder you'll find a file per crash. Look at the top for the description of the cause and search the error message for a mod name; it's often stated literally.
• Logs: no crash report? Then logs/latest.log usually helps. Scroll to the last error before the shutdown.
• Memory errors: if you see out-of-memory errors, your RAM allocation is too tight for the pack or the player count. Time to scale up.
• The halving method: if you can't figure it out, temporarily move half of the mods out of the mods folder and test again. In a few steps you'll circle in on the culprit.

And the most important habit of all: make a backup before every pack update. Rolling an update back is done in no time; restoring a corrupted world without a backup isn't.

Which MC-Node plan fits your modpack?

At MC-Node, your server runs on our own hardware with NVMe storage in the Previder data center in Hengelo, including DDoS protection. All plans can be cancelled monthly, so you can start small and scale up once your pack or player group calls for it. As a guide, a selection of the Minecraft plans — exact specifications per plan are on the plan page:

Most plans also come in a Premium variant. See all Minecraft plans and current specs in the MC-Node store. Torn between two sizes? Feel free to start one size smaller: you can always upgrade, and this way you're not paying for memory your pack doesn't use.