Blueprint could not be loaded because it derives from an invalid class

Hello I’m a student working on a team project and we are using GitHub for source control for our project. This is the first time using both Unreal Engine and Github so there is a bit of a learning curve.

The problem I currently have is that I am getting the following message when I try to open a blueprint:

Blueprint could not be loaded because
it derives from an invalid class.
Check to make sure the parent class
for this blueprint hasn’t been

So this Blueprint is derived from a Character class I have created in C++ using Visual Studio following the FPS shooter tutorial on the wiki. both the blueprint and class worked fine while I was at University where I first created the code. I then committed the changes and synced them to Github.

The problem arose after I got home and pulled those changes from Github to my local repo to try and continue work on the project.

The character class is still showing in the Visual Studio Solution and it builds successfully, but then I have the error when I try to open the blueprint in the Unreal Engine Editor.

I am also not able to see the Game Mode class from within the game mode drop down in the project settings that I think would be caused by the same issue.

So this leads me to believe that the Unreal Engine Editor is not able to locate the classes I have created, I think this might be caused by some file not being committed to the GitHub.

So I would like to know if there is a way to fix the error and secondly was it caused by the source control not committing some file the engine needs, I don’t want this to be a continuing problem in the future.

Additional information:

  • Using Unreal Engine 4.6.1
  • Using Visual Studio 2013 Community Edition W/ build in Git Tools

The .uproject file for a source-based project has a Modules section that points to the UE4Editor-MyProject.dll that contains your C++ code. I suspect you initially created your project as BP only, submitted your .uproject file to source control, added source to your project, and didn’t submit the updated .uproject file. When you sync up on the other machine, you have the source but your project is still being treated as BP only because of the outdated .uproject file.