How to Install a Modpack on Your Minecraft Server

Installing a modpack on a server trips up a lot of newcomers, because the pack you download for single-player is a client pack — it is not the same thing your server needs. This guide covers both the easy path (a one-click install from the panel) and the manual path (uploading a server pack yourself), then how to allocate RAM correctly so the pack actually stays online. Not sure which pack to run yet? Browse the modpack hosting hub first.

Client pack vs server pack — what is the difference?

A modpack ships in two flavours. The client version includes rendering, sound, and UI mods that a headless server neither needs nor can run. The server version strips those out and is meant to run without a graphical client. If you upload a client pack to a server, it will usually crash on startup complaining about client-only mods. Always grab the server files, or let the panel do it for you.

The easy way: one-click install from the panel

Every Prism Nodes server runs on our Pterodactyl-based panel with a built-in mod and modpack installer, so most popular packs are one click away:

1. Log in to your server from the billing portal and open the panel.
2. Go to the Startup or Settings area and choose the modpack installer.
3. Search for your pack (for example All the Mods 10 or RLCraft) and select the version you want.
4. Confirm — the panel downloads the correct server pack, installs the loader, and sets the startup command for you.
5. Start the server and watch the console until you see the "Done" line.

That is it — no manual file wrangling. This is the recommended route for anything in our catalogue, such as All the Mods 10 or RLCraft.

The manual way: uploading a server pack

For a pack the installer does not list, or a custom/private pack, upload it yourself:

1. Download the server pack from the pack's page (usually a separate "Server Files" download, not the client zip).
2. In the panel, stop the server and open the File Manager.
3. Upload the server-pack zip and extract it into the server root.
4. Some packs include a start script that downloads Forge/NeoForge/Fabric and its libraries on first run — run it once if present, or set the loader jar as your startup jar.
5. Set the correct startup command to point at the loader's launch jar (modern Forge/NeoForge use a generated args file rather than a single fat jar).
6. Accept the EULA (set eula=true in eula.txt) and start the server.

How much RAM should I allocate?

Modpacks are memory-hungry — a heavy pack can need 8-12 GB before a single player joins. Get a tailored number from the Minecraft RAM calculator, then allocate it correctly:

• Set min and max heap equal, for example -Xms8G -Xmx8G. This stops the JVM resizing the heap at runtime, which causes stutter.
• Leave headroom for the OS and off-heap memory — never hand the whole machine's RAM to the heap.
• Use Aikar's flags — a well-known set of G1GC tuning flags — on large heaps to smooth out garbage-collection pauses. They make a real difference on 8 GB+ modded servers.

Common pitfalls

• Uploading the client pack — the number-one crash cause. Always use server files.
• Mismatched loader version — the Forge/NeoForge/Fabric build must match what the pack expects, down to the minor version.
• Too little RAM — the server crashes on startup with an OutOfMemoryError, or limps at low TPS. Bump it up and restart.
• Adding client-only mods to the server — optifine-style and rendering mods belong on the client, not the server.
• Forgetting the EULA — the server refuses to start until you set eula=true.
• Version drift — do not mix mods from one Minecraft version with a loader built for another.

My modpack still will not start — what now?

Read the console top to bottom. Modded crash logs usually name the exact offending mod or the missing dependency in the first error block. A missing-dependency error means you need to add another mod; a client-class error means a client-only mod slipped into the server; an OutOfMemoryError means raise the RAM. If you are stuck, our support team can look at the log with you.

Once it boots cleanly, pick your pack from the modpack hub, confirm your allocation in the RAM calculator, and you are ready to invite players.

Frequently asked

Do I need the server pack or the client pack? The server pack. The client pack contains rendering and UI mods a server cannot run and will crash on.

How much RAM does a modpack server need? Light packs want 6-8 GB, heavy kitchen-sink packs 10-12 GB or more. Use the RAM calculator for your exact case.

What are Aikar's flags? A widely used set of G1GC JVM tuning flags that reduce garbage-collection lag spikes on large modded heaps.