Troubleshooting TiledMapTilesetProcessor Error

During the migration from MonoGame.Extended 3 to MonoGame.Extended 4, I came across a Processor 'TiledMapTilesetProcessor' had unexpected failure! error with the new version of the MonoGame Content Builder (MGCB). In this article, I explain how to solve the issue.

Context
Upgrade to MonoGame.Extended 4 with MonoGame 3.8.4

TiledMapTilesetProcessor Error and Solution

When building maps created with the Tiled (mapeditor.org) tool, the dotnet mgcb command line execution gave me a Processor 'TiledMapTilesetProcessor' had unexpected failure! error on all .tmx files.
This is a breaking change introduced by MonoGame 3.8.1.303. Here is how to solve this issue.

Problem Summary

After upgrading to MonoGame 3.8.1.303 and MonoGame.Extended 4.1.0 (with .NET 8), you may encounter this error when building Tiled maps with the content pipeline:

Processor 'TiledMapTilesetProcessor' had unexpected failure!
System.MissingMethodException: Method not found:
    'Microsoft.Xna.Framework.Color Microsoft.Xna.Framework.Color.get_TransparentBlack()'.

This is a common issue for developers migrating from MonoGame 3.8.0/MonoGame.Extended 3.x to the latest versions.

Why This Happens

• MonoGame 3.8.1.303 removed the deprecated property Color.TransparentBlack from the framework.
• Older versions of MonoGame.Extended (including some 4.x releases) still reference this property in their Tiled content pipeline processors.
• When the processor runs, it fails with a MissingMethodException because the property no longer exists in the updated MonoGame assemblies.

How to Fix

1. Update MonoGame Framework to 3.8.4

Migrate your MonoGame project to the version 3.8.4: see this post for a step-by-step guide.

Why?
MonoGame 3.8.4 is fully compatible with .NET 8 and recent MonoGame.Extended releases.

2. Update MonoGame.Extended Content Pipeline Packages

• Ensure you are using the latest MonoGame.Extended 4.1.0 NuGet packages for both your runtime and content pipeline projects.
• Specifically, update:
  • MonoGame.Extended
  • MonoGame.Extended.Content.Pipeline

Check your .csproj and Content.mgcb references. The correct versions as of July 2025 are:

<PackageReference Include="MonoGame.Extended" Version="4.1.0" />
<PackageReference Include="MonoGame.Extended.Content.Pipeline" Version="4.1.0" />

3. Check the Project Configuration

Ensure the .csproj file contains this configuration:

    <PropertyGroup>
        <MonoGameExtendedPipelineReferencePath>$(MSBuildThisFileDirectory)pipeline-references</MonoGameExtendedPipelineReferencePath>
    </PropertyGroup>

And the /reference property from the Content/Content.mgcb file must be:

#-------------------------------- References --------------------------------#

/reference:../pipeline-references/MonoGame.Extended.Content.Pipeline.dll

4. Clean and Rebuild

• Delete all bin and obj folders in your solution.
• Rebuild your solution and content pipeline.

5. If the Error Persists

• If you still get the error after updating, try the following:

  • Add the MonoGame.Extended MyGet feed to your NuGet.config:

    <packageSources>
      <add key="lithiumtoast" value="https://www.myget.org/F/lithiumtoast/api/v3/index.json" />
      <add key="NuGet" value="https://api.nuget.org/v3/index.json" />
    </packageSources>

  • Install the latest pre-release versions (e.g., 3.9.0-alpha0093 or newer) for the content pipeline packages.

6. Check for DLL Mismatches

• Ensure that the version of MonoGame.Extended.Content.Pipeline.dll referenced in your content project matches the runtime version.
• Remove any old or manually-copied DLLs from your content pipeline directories.

Additional Tips

• If you are using Tiled maps with features like “infinite maps” or “chunks,” try exporting your maps with a fixed size, as some features may not be fully supported by the current MonoGame.Extended pipeline.
• Always verify that your .tmx files and content pipeline tools are up-to-date and compatible with your MonoGame.Extended version.

Troubleshooting Checklist

• Update to MonoGame.Extended 4.1.0 (or latest pre-release if needed)
• Update MonoGame.Extended.Content.Pipeline to the same version
• Ensure .csproj and Content.mgcb reference correct DLLs and paths
• Clean all bin and obj folders
• Remove any old or mismatched DLLs from pipeline directories
• If error persists, add MyGet feed and try latest pre-release
• Export Tiled maps with fixed size if using “infinite” maps

By following these steps, you should be able to resolve the TiledMapTilesetProcessor error and successfully build your Tiled maps with MonoGame.Extended 4 and MonoGame 3.8.1.