How to Upload and Install a Custom Modpack

If your modpack isn't listed in Modpack Installer, you'll need to upload it manually: compress your local mods folder into a zip, upload it through Files, then strip out any client-only mods before restarting. This is the standard path support uses for custom or niche modpacks that aren't in the built-in catalog.

Symptoms

• Your modpack doesn't appear when searching Modpack Installer
• You uploaded a zip but the server still won't start
• Players get kicked or can't connect even though the server shows Online
• Console shows a crash tied to a specific mod right after startup

Why this happens

Custom or smaller modpacks often aren't indexed in the panel's Modpack Installer catalog, so there's no automatic way to pull them in. You have to move the files yourself. The most common failure after upload isn't the upload itself, it's what's inside the folder: modpacks bundle client-side mods (visual, sound, UI, and performance mods like Oculus, Embeddium, or sound/texture packs) that only run in the player's game. A dedicated server has no renderer or GUI, so these mods fail to load and can stop the whole server from booting. Mismatched mod versions and missing dependencies cause the same kind of crash.

How to fix it

1. On your PC, locate the modpack's mods folder (inside your CurseForge/Modrinth instance) and compress it into a single .zip file.
2. Open Files on your server and upload that zip into the existing mods directory.
3. Delete the old mods folder if one exists, then extract the uploaded zip so the files land directly in the mods folder.
4. Open Console and start the server. If it crashes, check the log for the mod name causing the failure.
5. Remove any client-side-only mods (visual, sound, UI, or performance mods) from the server's mods folder: they don't belong there and will block startup.
6. If the crash log points to a missing mod, install the missing dependency the same way.
7. Restart the server, confirm it reaches Online, then connect from your own game: you'll need the identical modpack installed locally through CurseForge or your launcher to join.

Never leave client-side-only mods (rendering, sound, or UI mods) in the server's mods folder. They're a leading cause of servers that won't boot after a custom modpack upload.

Before doing a big pack swap, check your Backups first so you can roll back if the new pack corrupts your world. Also confirm your plan has enough RAM for the pack's requirements, see How Much RAM Does Your Modded Minecraft Server Need?

Still stuck?

If the server still won't start after removing client-side mods, read the crash trace carefully using Minecraft Server Won't Start: How to Read the Crash Log, or check Fix "Missing Dependency" and Mod Conflict Errors. If your pack is available through the catalog, it's much simpler to use How to Install a Modpack with the 1-Click Installer instead. Once you're in, set yourself up with How to Give Yourself Operator (OP) Permissions. Still broken after all that? Open a support ticket with your Console crash log attached, our team can trace the exact mod causing the failure.