[Bug]: MelonLoader makes Overcooked! 2 crash before startup on Linux

All of the following criteria must be met

All Requirements must be installed.
Changed the title so that it doesn't just says "[Bug]: "
I have searched the GitHub issues for my bug, even in the closed issues.

All of the following are optional to answer

Tried reinstalling the Game.
Tried reinstalling MelonLoader.
Tried restarting PC.

Describe the issue.

I have installed Overcooked! 2 from Steam on Linux (Fedora 44). Everything is working fine. I want to install MelonLoader over it. I have run MelonLoader.Installer.Linux and installed MelonLoader 7.3 on Overcooked!2 (some other project seem successful with it: https://github.com/RizkyChandra/overcooked-2-mod#overcooked-2-trainer-melonloader-mod ).
However, just after installing MelonLoader (no mods, nothing beyond what installer did), I cannot start the game and instead have this error in log:

Log says

 
(Filename:  Line: 199)

Mono path[0] = '/run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Managed'
Mono config path = '/run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/etc'
[22:40:30.714] [WARNING] AccessTools.Method: Could not find method for type System.Exception and name PrepForRemoting and parameters 
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/data-0x310c95c0.so

[22:40:31.018] ------------------------------
[22:40:31.048] MelonLoader v0.7.3 Open-Beta
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/ntdll.dll
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/libntdll.dll.so
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/./ntdll.dll
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/./libntdll.dll.so
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/ntdll.dll
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/ntdll
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/libntdll.so
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/./ntdll
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/./libntdll.so
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/ntdll
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/libntdll.dll
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/libntdll.dll.so
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/./libntdll.dll
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/./libntdll.dll.so
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/libntdll.dll
[22:40:31.058] OS: Unix 7.2.5.200
[22:40:31.058] Hash Code: 299FFEE557A53F007B5BCEF4CCD23994F4E76F636A4DF86FCB1729D1296049D2
[22:40:31.058] ------------------------------
[22:40:31.232] Game Type: MonoBleedingEdge
[22:40:31.232] Game Arch: x64
[22:40:31.233] ------------------------------
[22:40:31.233] Command-Line: 
[22:40:31.233] ------------------------------
[22:40:31.233] Core::BasePath = /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2
[22:40:31.234] Game::BasePath = /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2
[22:40:31.234] Game::DataPath = /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data
[22:40:31.234] Game::ApplicationPath = /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2.x86_64
[22:40:31.234] Runtime Type: net35
[22:40:31.366] ------------------------------
[22:40:31.366] Game Name: Overcooked2
[22:40:31.366] Game Developer: Team17
[22:40:31.368] Unity Version: 2017.4.8f1
[22:40:31.368] Game Version: 1.0
[22:40:31.368] ------------------------------

Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/data-0x31514340.so
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/data-0x3153b710.so
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/data-0x31554920.so
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/data-0x3154a390.so
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/data-0x31559ce0.so
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/data-0x315b1300.so
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/data-0x315bbe40.so
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/data-0x315b9a20.so
Fallback handler could not load library /run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/data-0x315d5d20.so
[22:40:31.560] [ERROR] Failed to initialize MelonLoader
[22:40:31.564] [ERROR] [MelonLoader.Bootstrap] System.TypeInitializationException: An exception was thrown by the type initializer for MelonLoader.MelonPreferences ---> System.TypeInitializationException: An exception was thrown by the type initializer for MelonLoader.TomlMapper ---> System.TypeInitializationException: An exception was thrown by the type initializer for Tomlet.TomlSerializationMethods ---> System.TypeLoadException: Could not load type 'Typespec 0x1b000001'.
  at (wrapper managed-to-native) System.MonoType:GetMethodsByName (string,System.Reflection.BindingFlags,bool,System.Type)
  at System.MonoType.GetMethodImpl (System.String name, BindingFlags bindingAttr, System.Reflection.Binder binder, CallingConventions callConvention, System.Type[] types, System.Reflection.ParameterModifier[] modifiers) [0x00000] in <filename unknown>:0 
  at System.Type.GetMethod (System.String name, BindingFlags bindingAttr) [0x00000] in <filename unknown>:0 
  at Tomlet.TomlSerializationMethods..cctor () [0x00000] in <filename unknown>:0 
  --- End of inner exception stack trace ---
  at Tomlet.TomletMain.RegisterMapper[LemonTuple`2] (Tomlet.Serialize`1 serializer, Tomlet.Deserialize`1 deserializer) [0x00000] in <filename unknown>:0 
  at MelonLoader.TomlMapper..cctor () [0x00000] in <filename unknown>:0 
  --- End of inner exception stack trace ---
  at MelonLoader.MelonPreferences..cctor () [0x00000] in <filename unknown>:0 
  --- End of inner exception stack trace ---
  at MelonLoader.Core.Initialize () [0x00000] in <filename unknown>:0 
  at MelonLoader.InternalUtils.BootstrapInterop.Initialize (IntPtr bootstrapHandle) [0x00000] in <filename unknown>:0 
**
GLib:ERROR:../../../glib/ghash.c:378:g_hash_table_lookup_node: assertion failed: (!g_atomic_ref_count_compare (&hash_table->ref_count, 0))
Stacktrace:


Native stacktrace:

	/run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2_Data/Mono/x86_64/libmono.so(+0x9843a) [0x7ed9eba9843a]
	/usr/lib/pressure-vessel/overrides/lib/x86_64-linux-gnu/libc.so.6(+0x19faf) [0x7f1aa7220faf]
	/usr/lib/pressure-vessel/overrides/lib/x86_64-linux-gnu/libc.so.6(+0x74ccc) [0x7f1aa727bccc]
	/usr/lib/pressure-vessel/overrides/lib/x86_64-linux-gnu/libc.so.6(gsignal+0x1d) [0x7f1aa7220e8d]
	/usr/lib/pressure-vessel/overrides/lib/x86_64-linux-gnu/libc.so.6(abort+0x25) [0x7f1aa72087b2]
	/lib/x86_64-linux-gnu/libglib-2.0.so.0(+0x1bdc2) [0x7ed9eb112dc2]
	/lib/x86_64-linux-gnu/libglib-2.0.so.0(g_assertion_message_expr+0x49) [0x7ed9eb16cc19]
	/lib/x86_64-linux-gnu/libglib-2.0.so.0(+0x3c0a5) [0x7ed9eb1330a5]
	/lib/x86_64-linux-gnu/libgobject-2.0.so.0(+0x2f15e) [0x7ed9ebfb315e]
	/lib/x86_64-linux-gnu/libgobject-2.0.so.0(+0x2f32a) [0x7ed9ebfb332a]
	/lib/x86_64-linux-gnu/libgobject-2.0.so.0(+0xb8da) [0x7ed9ebf8f8da]
	/lib64/ld-linux-x86-64.so.2(+0x53ee) [0x7f1aa88893ee]
	/lib64/ld-linux-x86-64.so.2(+0x54cc) [0x7f1aa88894cc]
	/lib64/ld-linux-x86-64.so.2(_dl_catch_exception+0x156) [0x7f1aa88857d6]
	/lib64/ld-linux-x86-64.so.2(+0xc598) [0x7f1aa8890598]
	/lib64/ld-linux-x86-64.so.2(_dl_catch_exception+0xa8) [0x7f1aa8885728]
	/lib64/ld-linux-x86-64.so.2(+0xca69) [0x7f1aa8890a69]
	/usr/lib/pressure-vessel/overrides/lib/x86_64-linux-gnu/libc.so.6(+0x6f0c3) [0x7f1aa72760c3]
	/lib64/ld-linux-x86-64.so.2(_dl_catch_exception+0xa8) [0x7f1aa8885728]
	/lib64/ld-linux-x86-64.so.2(+0x1878) [0x7f1aa8885878]
	/usr/lib/pressure-vessel/overrides/lib/x86_64-linux-gnu/libc.so.6(+0x6ebb2) [0x7f1aa7275bb2]
	/usr/lib/pressure-vessel/overrides/lib/x86_64-linux-gnu/libc.so.6(dlopen+0x6a) [0x7f1aa727617a]
	/run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2.x86_64() [0x1286a00]
	/run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2.x86_64() [0x45f564]
	/tmp/pressure-vessel-libs-1lVKCV/lib64/MelonLoader.Bootstrap.so(+0x5daa7f) [0x7f1aa7ddaa7f]
	/tmp/pressure-vessel-libs-1lVKCV/lib64/MelonLoader.Bootstrap.so(+0xe2605) [0x7f1aa78e2605]
	/usr/lib/pressure-vessel/overrides/lib/x86_64-linux-gnu/libc.so.6(+0x3680) [0x7f1aa720a680]
	/usr/lib/pressure-vessel/overrides/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x87) [0x7f1aa720a797]
	/tmp/pressure-vessel-libs-1lVKCV/lib64/MelonLoader.Bootstrap.so(+0xe2bdc) [0x7f1aa78e2bdc]
	/tmp/pressure-vessel-libs-1lVKCV/lib64/MelonLoader.Bootstrap.so(__libc_start_main+0x11e) [0x7f1aa78e252e]
	/run/media/mistria/229F5A9322A00041/steam/steamapps/common/Overcooked! 2/Overcooked2.x86_64() [0x46d208]

Debug info from gdb:


=================================================================
Got a SIGABRT while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries 
used by your application.
=================================================================

I tried to understand the error, but my knowledge of C# is too thin to help me.
Does anyone have any hint of a potential cause and solution?

Did you attach your log file?

Yes, I attached my log file to the text box above.

I could investigate it and it seems rather independent from MelonLoader and entirely caused by an incompatibility of Tomlet with the Mono version (2.6.5.tarball) included in Overcooked 2.

To build a Tomlet-only (no Unity, no MelonLoader) reproducer:

Let's assume there is a OVERCOOKED_INSTALL_DIR environment variable pointing to the folder where Overcooked2 in installed, eg to /home/me/.steam/steam/steamapps/common/Overcooked! 2; and let's assume there is a random folder such as home/me/sandbox where to put some mess.

Create a basic C program to start Mono programatically (so does the Overcooked2.x86_64 executable):

Inspired from https://www.mono-project.com/docs/advanced/embedding/ . this will allow to have an executable able to start any .net program with the embedded mono from Overcooked2.

Code:

#include <mono/jit/jit.h>
#include <mono/metadata/assembly.h>

int main(int argc, char** argv) {
	MonoDomain *domain = mono_jit_init ("Test random .NET program with embedded mono");
	MonoAssembly *assembly = mono_domain_assembly_open (domain, argv[1]);
	return mono_jit_exec (domain, assembly, argc - 1, argv + 1);
}

Compile it with gcc -I/usr/lib64/pkgconfig/../../include/mono-2.0 testMono.c -L"/$OVERCOOKED_INSTALL_DIR/Overcooked2_Data/Mono/x86_64" -l:libmono.so -o testMono

Workaround library name trouble with ln -s "$OVERCOOKED_INSTALL_DIR/Overcooked2_Data/Mono/x86_64/libmono.so" "$OVERCOOKED_INSTALL_DIR/Overcooked2_Data/Mono/x86_64/libmono.so.0"

Verify this works and get libmono version

Under /home/me/sandbox/hello

Hello.csproj

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net35</TargetFramework>
    <GenerateRuntimeConfigurationFiles>true</GenerateRuntimeConfigurationFiles>
  </PropertyGroup>
</Project>

Hello.cs

using System.Reflection;
using System;

namespace Hello {
	class Hello {
	  static void Main(string[] args)
	  {
			Type type = Type.GetType("Mono.Runtime");
if (type != null)
{
    MethodInfo displayName = type.GetMethod("GetDisplayName", BindingFlags.NonPublic | BindingFlags.Static);
    if (displayName != null)
        Console.WriteLine(displayName.Invoke(null, null));
}
		}
	}
}

The dotnet build it and then run it with our just built launcher and the embedded mono: MONO_PATH="$(pwd)/Overcooked2_Data/Managed" LD_LIBRARY_PATH="$(pwd)/Overcooked2_Data/Mono/x86_64:$LD_LIBRARY_PATH" ./testMono /home/mistria/sandbox/hello/bin/Debug/net35/Hello.exe
Get the expected output 2.6.5 (tarball), confirming that we are indeed the embedded mono.

Create a basic C# project that uses Tomlet and Framework version similar to Overcooked2

Test.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net35</TargetFramework>
    <GenerateRuntimeConfigurationFiles>true</GenerateRuntimeConfigurationFiles>
  </PropertyGroup>

  <ItemGroup>
  	<!-- Same as in Overcooked: `monodis -assembly "$(pwd)/MelonLoader/net35/Tomlet.dll" | grep Version` -->
    <PackageReference Include="Samboy063.Tomlet" Version="6.2.0" />
  </ItemGroup>

</Project>

and Test.cs

using Tomlet;
using Tomlet.Attributes;

namespace Test {
	
	class MyClass {
	    [TomlProperty("name")]
	    public string Username { get; set; }
	}
	
	class Test {
	  static void Main(string[] args)
	  {
			var myClass = TomletMain.To<MyClass>("name=\"hello\""); //Requires a public, zero-argument constructor on MyClass.
			System.Console.WriteLine(myClass.Username);
		}
	}
}

compile with dotnet build, assume output is /home/me/sandbox/bin/Debug/net35/Test.exe.

Run test with embedded mono

From $OVERCOOKED_INSTALL_DIR, run MONO_PATH="$(pwd)/Overcooked2_Data/Managed" LD_LIBRARY_PATH="$(pwd)/Overcooked2_Data/Mono/x86_64:$LD_LIBRARY_PATH" ./testMono /home/mistria/sandbox/bin/Debug/net35/Test.exe

EXPECTED: console saying "hello"
GOT:

type 0x1f not handled in do_mono_metadata_parse_type on image /home/mistria/sandbox/bin/Debug/net35/Tomlet.dll
The class Typespec 0x1b000001 could not be loaded, used in 

Unhandled Exception: System.TypeInitializationException: An exception was thrown by the type initializer for Tomlet.TomlSerializationMethods ---> System.TypeLoadException: Could not load type 'Typespec 0x1b000001'.
  at (wrapper managed-to-native) System.MonoType:GetMethodsByName (string,System.Reflection.BindingFlags,bool,System.Type)
  at System.MonoType.GetMethodImpl (System.String name, BindingFlags bindingAttr, System.Reflection.Binder binder, CallingConventions callConvention, System.Type[] types, System.Reflection.ParameterModifier[] modifiers) [0x00000] in <filename unknown>:0 
  at System.Type.GetMethod (System.String name, BindingFlags bindingAttr) [0x00000] in <filename unknown>:0 
  at Tomlet.TomlSerializationMethods..cctor () [0x00000] in <filename unknown>:0 
  --- End of inner exception stack trace ---
  at Tomlet.TomletMain.To (System.Type what, Tomlet.Models.TomlValue value, Tomlet.TomlSerializerOptions options) [0x00000] in <filename unknown>:0 
  at Tomlet.TomletMain.To (System.Type what, System.String tomlString, Tomlet.TomlSerializerOptions options) [0x00000] in <filename unknown>:0 
  at Tomlet.TomletMain.To[MyClass] (System.String tomlString, Tomlet.TomlSerializerOptions options) [0x00000] in <filename unknown>:0 
  at Test.Test.Main (System.String[] args) [0x00000] in <filename unknow

This is caused by SamboyCoding/Tomlet#65 .

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[Bug]: MelonLoader makes Overcooked! 2 crash before startup on Linux #1202

All of the following criteria must be met

All of the following are optional to answer

Describe the issue.

Did you attach your log file?

Create a basic C program to start Mono programatically (so does the Overcooked2.x86_64 executable):

Verify this works and get libmono version

Create a basic C# project that uses Tomlet and Framework version similar to Overcooked2

Run test with embedded mono

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[Bug]: MelonLoader makes Overcooked! 2 crash before startup on Linux #1202

Description

All of the following criteria must be met

All of the following are optional to answer

Describe the issue.

Did you attach your log file?

Activity

mickaelistria commented on Sep 22, 2026

Create a basic C program to start Mono programatically (so does the Overcooked2.x86_64 executable):

Verify this works and get libmono version

Create a basic C# project that uses Tomlet and Framework version similar to Overcooked2

Run test with embedded mono

mickaelistria commented on Sep 23, 2026

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