Understanding Why Your MelonLoader or Lemon Loader Isn’t Working—And How to Fix It

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It’s a frustratingly familiar scenario for PC gamers and modding enthusiasts: you’ve installed MelonLoader or Lemon Loader, followed all the YouTube tutorials, even tried multiple versions like 0.6.1 or 1.0.0, and yet—your game stays stubbornly unmodded.

While it might feel like you’re doing everything right, modding Unity games—especially with tools like MelonLoader (the foundation of Lemon Loader for Bonelab on PC)—isn’t always plug-and-play. Behind the scenes is a delicate chain of dependencies, compatibility requirements, and installation protocols. If just one link breaks, the whole process fails.

Let’s break down the most common reasons why your loader isn’t working—and how to solve them.

🔗 The Core Problem: A Chain of Specific Requirements

MelonLoader must hook into Unity’s startup process to load your mods. To do that successfully, it needs:

  • The right Unity version
  • Correct runtime libraries
  • Clean and proper installation
  • A cooperative antivirus
  • And often, mod-specific compatibility

Let’s dig into the most common failure points.

🧩 1. Version Mismatch: Game vs. MelonLoader

This is the #1 issue by far. MelonLoader versions are tightly coupled to specific Unity versions and scripting backends.

Key Factors:

  • Unity Engine Changes Frequently: A game using Unity 2018.x won’t work with a MelonLoader meant for Unity 2021.x or 2022.x.
  • Game Patches Break Compatibility: Even a minor update might switch Unity versions or change from Mono to Il2Cpp.
  • Mono vs. Il2Cpp: The scripting backend (Mono or Il2Cpp) impacts how MelonLoader must operate. Some versions support one better than the other.

✅ Your Action Plan:

  1. Identify Your Game’s Unity Version:
    • Go to the game’s install folder.
    • Right-click the .exe > Properties > Details.
    • Look for the Product/Version string (it may hint at the Unity version).
    • For precise info, check modding forums or community wikis for your game (e.g., Bonelab communities often recommend MelonLoader 0.6.5).
  2. Download the Correct MelonLoader Version:
    • Visit the MelonLoader or its wiki.
    • Match the MelonLoader version to your Unity version and scripting backend.

🧱 2. Missing Dependencies: Visual C++ & .NET Runtime

MelonLoader is written in C# and depends on Microsoft’s runtime libraries. If they’re missing or outdated, it simply won’t run.

What You Need:

  • Microsoft Visual C++ Redistributables:
    • Install both x86 and x64 versions of the 2015–2019 (or newer) packages.
  • .NET Desktop Runtime:
    • Required for modern MelonLoader versions like 0.6.x and 1.0.0.
    • Install .NET 6.0, 7.0, or 8.0 Desktop Runtime, matching the version required by your loader.

✅ Your Action Plan:

  1. Go to Control Panel > Programs > Programs and Features.
  2. Look for:
    • Microsoft Visual C++ Redistributable
    • Microsoft .NET Desktop Runtime
  3. If missing or outdated:
    • Download the Visual C++ Redistributables here.
    • Get the correct .NET Desktop Runtime here.

💡 Be sure to install the “Desktop” runtime, not just the base runtime.

🧼 3. Improper Installation or Conflicting Files

Even if you used the correct MelonLoader version, bad file placement or leftover junk can ruin everything.

Common Issues:

  • Wrong File Location: version.dll, MelonLoader, and the Mods folder must be in the same directory as your game’s .exe.
  • Leftover Garbage: Previous mod attempts may leave broken files behind (like old DLLs).
  • Antivirus Quarantine: Many AV tools auto-delete files like version.dll because it injects into other programs.

✅ Your Action Plan:

  1. Clean Uninstall:
    • Fully exit the game.
    • Delete the following from the install folder:
      • MelonLoader folder
      • version.dll, dobby.dll, notice.txt, etc.
      • (Optional) Delete Mods, Plugins, UserLibs, and UserData.
  2. Verify Game Files:
    • For Steam: Right-click game > Properties > Installed Files > Verify integrity.
  3. Reinstall MelonLoader:
    • Use the official automated installer when possible.
    • If manual:
      • Extract all files from the .zip into the game folder.
      • Make sure version.dll is present next to the .exe.
  4. Antivirus Exception:
    • Temporarily disable your AV during install.
    • Afterward, add an exception for your game folder and the MelonLoader folder.

🎮 4. Game-Specific Issues & Mod Conflicts

Sometimes the problem lies not with MelonLoader—but with the mods themselves, or how your game is built.

Examples:

  • Game Platform Issues:
    • Games from Xbox Game Pass or Epic may have DRM or strange file structures that require special steps.
  • Conflicting or Outdated Mods:
    • One bad mod can break everything. Even if MelonLoader loads, a bad mod can crash the game or prevent other mods from working.

✅ Your Action Plan:

  1. Check Game-Specific Communities:
    • Discord servers, subreddits, or modding forums are invaluable. Someone has likely faced your exact problem.
  2. Isolate Mods:
    • Remove all mods from the Mods and Plugins folders.
    • Launch the game. If it works, reintroduce mods one at a time.

🪵 5. The MelonLoader Log File: Your Secret Weapon

When MelonLoader fails, it doesn’t leave you in the dark. It logs everything.

✅ Your Action Plan:

  1. Find the Log:
    • Go to your game folder > MelonLoader > Logs.
    • Open latest.log with a text editor.
  2. Look for Clues:
    • Search for lines starting with [ERROR] or [WARNING].
    • Key phrases include:
      • System.IO.FileNotFoundException
      • System.TypeLoadException
      • Failed to load
      • Cpp2IL download failed

This will often pinpoint the exact issue, whether it’s a missing runtime, a corrupt mod, or even a typo in your file structure.

🛠️ Final Thoughts: Solve the Puzzle, Enjoy the Mods

Modding with MelonLoader (or Lemon Loader) isn’t magic—it’s engineering. Each piece must fit. But once you’ve identified your Unity version, verified dependencies, cleaned the install, and checked your mods, your game should finally launch with all the custom content you’ve been hoping for.

Be patient. Be methodical. And lean on the community—they’re your best allies in the modding world.

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