How to Set Up a Modded Minecraft Server (Modpacks)
Set up a modded Minecraft server or a modpack: pick the loader and version, size the RAM, install mods and share a matching pack with your players.
To set up a modded Minecraft server, pick the modpack or mod list first, then use the exact loader and Minecraft version it requires, give the server enough RAM, install the mods and make sure every player has the matching client-side mods. The loader and version are not flexible: the mods decide them. Get that right and most of the usual errors never appear.
Step 1: Decide what you are running
There are two starting points.
- A ready-made modpack from CurseForge, FTB or Modrinth. It comes with the loader, version and mod list already chosen. This is the easiest route, and the one for most people.
- Your own mod list, picked mod by mod. You pick the loader (Fabric, NeoForge, Forge or Quilt) and a Minecraft version that all your mods support. See Paper vs Spigot vs Forge vs Fabric if you are choosing between loaders.
If you are not sure that mods are what you want, read plugins vs mods first. Many servers that think they need mods are better served by plugins.
Step 2: Check the requirements
Before downloading anything, open the modpack or mod page and note:
- The Minecraft version and the loader (and its version, for Forge and NeoForge).
- Whether there is a server pack or server files. Some packs include client-only mods that crash a server.
- The recommended RAM from the author.
- The Java version. Each Minecraft version needs a specific Java: too old and it will not start, too new and some mods fail.
Step 3: Size the memory
Modpacks are heavy. A light pack of a few dozen mods can run on modest memory with a handful of players, while a large pack with hundreds of mods wants much more, and more again as players join. Use the author's recommendation as a floor and our RAM guide and the RAM calculator to sanity-check.
Avoid the instinct to simply allocate everything; an oversized heap makes garbage collection slower. If you notice stutters later, go to fixing server lag.
Step 4: Install the pack or the loader
On a self-managed machine, you install the loader with its own installer, accept the EULA, and place mods in the mods/ folder.
On a managed panel it is much shorter. In SolumeCore's Minecraft panel:
- Open the modpacks section and pick a CurseForge, FTB or Modrinth pack.
- Confirm. The panel switches the server to the pack's loader and reinstalls it. Your world is kept, but anything in your plugins or mods folders may clash with the pack, so take a backup first.
- Start the server and watch the console. The first start is slow because mods are generating their files.
For a custom list, use the content tab: it searches Modrinth filtered by your loader and version, so you cannot download the wrong build by accident, and it installs required dependencies.
Step 5: Make the players match
This is the number one source of "mismatched mod list" errors. Every player needs the same client-side mods, in the same versions, with the same loader.
You have three options:
- Ask players to install the same modpack from the same launcher.
- Send them a list and a link, and hope they follow it exactly.
- Give them one file. SolumeCore can build a player pack: a
.mrpackmade from the client-side mods on your server, with the correct loader and your server already in the Multiplayer list. Players open it in Prism Launcher, Modrinth App or CurseForge, and press Play.
Mods that are not hosted on Modrinth cannot be included in the generated file for licensing reasons; the panel lists them so you can tell players to get them by hand.
Step 6: Fix the common problems
| Symptom | Likely cause | Fix |
|---|---|---|
| Server never finishes starting | Not enough memory, or a mod crashing at load | Read the crash log; raise memory if it is out of memory |
| "Mismatched mod list" when joining | Player has different mods or versions | Give them the player pack |
| Server crashes immediately | A client-only mod on the server | Remove client-only mods; the panel's crash analysis flags this |
| A mod does nothing | Missing dependency | Install the dependency the mod page lists |
| Wrong Java error | Java version does not match the Minecraft version | Pick the right Java in the panel's Java section |
The panel's crash detection explains the cause of a crash in plain language and offers a one-click fix when there is one, such as installing a missing dependency.
Step 7: Back up before every change
Updating a modpack or adding a mod can corrupt a world, especially mods that add new blocks or dimensions. Make a backup before each change and keep at least one that you have confirmed works. More in how to back up a game server.
FAQ
Can I add mods to an existing Paper server?
Not directly. Paper loads plugins, not mods. You would switch to a mod loader, and plugins will stop working. See plugins vs mods.
How many mods can a server handle?
It depends less on the count than on what the mods do. A few heavy mods can cost more than a hundred light ones.
Do I need the same mods on the server and the client?
Content mods, yes. Server-side-only mods (for example, many optimization mods) need nothing on the client, and client-only mods (shaders, minimaps) should never be on the server.
Can I update the modpack later?
Yes, but treat it as a risky change: back up first, update the server and have your players update at the same time.
Why is my modded server slow to start?
Large packs load thousands of assets and registry entries. Several minutes is normal for big ones on first start.
Run it with a panel that fits
If you want modpack installs, a player pack and crash analysis without the manual work, see Minecraft server hosting. Questions on a specific error? Search the help center.