Upload a custom modpack or server pack

If the pack you want is not in the Modpacks tab's search, you can upload it yourself. The tab accepts a Modrinth .mrpack file or a server-pack .zip, unpacks it on your server and sets up the launch script. Installing a pack reinstalls the server, so your files are replaced by the pack's.

Checked against our installer, the Modrinth App support page, Prism Launcher's 7.0 release post and CurseForge's support pages, October 2026.

Which file to upload

• A .mrpack file. The Modrinth App makes one: open an instance, go to its Mods tab and press Export modpack. If the button is missing, the instance may need unpairing in its settings first. Prism Launcher can export Modrinth packs too, since version 7.0. The installer reads the pack's own list of files, installs the loader the pack names, downloads the mods and applies the pack's config. It skips any mod the pack marks as unsupported on servers.
• A server-pack .zip. This is a zip that already holds a server: a mods folder and configs, often with the loader. On CurseForge it is the file attached to the pack's main file as an "Additional File". A Technic pack that has a server download publishes it as a zip.
• A CurseForge profile export .zip. In the CurseForge app, open the profile's menu, choose Share Profile, tick config and mods, and export the zip. A zip with a manifest.json at its top and no mods folder is treated as a client export. The installer downloads the mods the manifest lists.

Match the server first

The upload does not carry a Minecraft version or loader to the server. It keeps whatever the server runs now, and Java follows that version. Open JAR Manager first and switch to the Minecraft version and loader the pack was built for. Change your Minecraft version or mod loader has the steps.

Upload and install

1. Open your server and choose Modpacks under Content in the left rail.
2. In the Install your own pack card, drop the file onto the box that says "Drop a .mrpack or a server-pack .zip", or click it to browse. Nothing installs yet.
3. Leave Take a backup first ticked. Tick Keep my world, settings and player lists if you want your current world, because otherwise the pack's world replaces it.
4. Press Install and reinstall, then hold the confirm button in the window that opens.
5. Watch the Console. When the install ends, press Start and accept the EULA if asked.

If there is no Install your own pack card, that option is not switched on for your account yet. Contact support.

What the installer does with a zip

It unpacks the zip into the server's root folder. If the pack sits one folder deep, it moves everything up. If the zip carries a loader installer jar, it runs it. If it finds no launcher after that, it reads a variables.txt in the zip. The file can hold these lines. Any you leave out fall back to the loader and Minecraft version the server already runs, and a missing MODLOADER_VERSION installs the loader's default build: Forge's recommended build (or its latest if there is no recommended one), the newest stable NeoForge build, and whatever the Fabric installer picks by default.

MODLOADER=NeoForge
MODLOADER_VERSION=your-loader-build
MINECRAFT_VERSION=1.21.1

Without a variables.txt it falls back to the loader the server already runs. It can install Fabric, Forge or NeoForge this way. A pack for any other loader can stop with "The pack installed, but no server engine could be set up for it".

If the install fails

When the panel records an install as failed, the tab shows "The last install didn't finish" with Show install log and Retry install. An install that carries on past an error is not always recorded that way: in our test a corrupt pack zip left the tab on Installed on this server with the pack name and no alert. So after any install that looks wrong, press Last install log in the Your packs card, which opens the raw installer text, including any unzip errors. A server that installs but will not start needs its crash report. Find and read a Minecraft server crash report shows where to look.

If the pack is a client pack with no server files, Turn a client modpack into a server pack explains how to prepare it first.