# MelonLoader Install & Version Management (/docs/schedule-1/melonloader)



import { Callout } from 'fumadocs-ui/components/callout';
import { Step, Steps } from 'fumadocs-ui/components/steps';

**MelonLoader** is the universal Unity mod loader from LavaGang. Every Schedule I mod — including the S1 DedicatedServerMod, S1API and MultiplayerPlus — needs MelonLoader running underneath. This guide covers what's already done for you on XGamingServer, and what to do if you self-host.

<Callout type="info">
  On every XGamingServer Schedule 1 plan, MelonLoader is **pre-installed at a known-good pinned version**. You normally don't need to touch it. This guide is for when you self-host, or when a Schedule I patch requires you to upgrade.
</Callout>

Version compatibility — the 0.7.1 trap [#version-compatibility--the-071-trap]

| MelonLoader version | Schedule I status                             |
| ------------------- | --------------------------------------------- |
| 0.6.x               | ✅ Supported                                   |
| 0.7.0               | ✅ Supported                                   |
| **0.7.1**           | ⚠️ **Avoid — known-bad with Schedule I mods** |
| 0.7.2+              | ✅ Supported                                   |

If you upgrade MelonLoader on a whim and end up on 0.7.1, mods will fail to load with strange `MissingMethodException` or `TypeLoadException` errors. **Downgrade to 0.7.0 or upgrade to 0.7.2+.**

Manual install (self-host) [#manual-install-self-host]

<Steps>
  <Step>
    **Find your Schedule I install path.** In Steam: right-click Schedule I → Manage → Browse local files. The folder will contain `Schedule I.exe`.
  </Step>

  <Step>
    **Download MelonLoader.** Get the latest **stable** release from [github.com/LavaGang/MelonLoader/releases](https://github.com/LavaGang/MelonLoader/releases). The installer is `MelonLoader.Installer.exe`.
  </Step>

  <Step>
    **Run the installer.** Point it at your Schedule I install folder. Pick **Il2Cpp** as the runtime (Schedule I is Il2Cpp on current builds; if you're on an older Mono build, pick Mono). Click Install.
  </Step>

  <Step>
    **Verify the install.** A new `MelonLoader/` folder and a `Mods/` folder appear next to `Schedule I.exe`. Launch the game once — MelonLoader's console window should open and show that no mods are loaded yet.
  </Step>

  <Step>
    **Pin the version.** Once your mods work, **stop letting MelonLoader auto-update**. Keep a backup copy of the MelonLoader folder so you can restore the working state if a future install breaks things.
  </Step>
</Steps>

Il2Cpp vs Mono [#il2cpp-vs-mono]

MelonLoader supports both Unity backends. Schedule I uses **Il2Cpp** on its current public release — that's the runtime to pick in the installer.

* **Il2Cpp** — Ahead-of-time compiled native code. Faster, smaller, harder to debug. Modern Unity default.
* **Mono** — JIT-compiled .NET runtime. Easier to mod. Older Unity default.

The S1 DedicatedServerMod supports both backends in its Docker images — pick the matching one via environment variable. On XGamingServer hosting, we use the Il2Cpp build to match the public Schedule I client.

Upgrading MelonLoader after a Schedule I patch [#upgrading-melonloader-after-a-schedule-i-patch]

When TVGS ships a Schedule I update, sometimes the Unity runtime changes (Il2Cpp version, .NET API surface) and MelonLoader needs to keep up. The sequence:

1. **Don't update immediately.** Wait until the S1 DedicatedServerMod author has tested and announced compatibility on the [GitHub releases page](https://github.com/ifBars/S1DedicatedServers/releases).
2. **Back up your save** before any version juggling. See [Backups & Restore](/docs/schedule-1/backup-restore).
3. **Update MelonLoader first**, then the DedicatedServerMod, then your content mods.
4. **Restart the server and check the MelonLoader console** for red `[ERR]` lines — those will name the mod that needs an update.

<Callout type="warn">
  On XGamingServer, we handle this version juggle for you. The panel ships a verified working MelonLoader + DedicatedServerMod set, and we ship updates after the upstream maintainer tags them stable.
</Callout>

Common MelonLoader errors [#common-melonloader-errors]

* **`MissingMethodException` on startup** — usually a MelonLoader / Schedule I version mismatch. Roll MelonLoader to the last known-good version.
* **MelonLoader window flashes and closes** — Schedule I is closing before MelonLoader writes anything. Run with `--melonloader.consoleAlwaysVisible` to keep the window open and read the error.
* **Mods folder ignored** — MelonLoader installed into the wrong folder. Re-run the installer and verify it's the folder containing `Schedule I.exe`.
* **`No bootstrap dll found`** — Il2Cpp install picked, but the game is on a Mono build (or vice-versa). Re-install with the correct runtime.

Related Guides [#related-guides]

* [DedicatedServerMod Setup →](/docs/schedule-1/dedicated-server-setup)
* [Install Mods →](/docs/schedule-1/install-mods)
* [Update Guide →](/docs/schedule-1/update-server)
* [Troubleshooting →](/docs/schedule-1/troubleshooting)