Can't open project after adding C++ class to blueprint project

Please, I need help.

I added a c++ class to my Blueprint Project. While creating the class it said that the class needed to be in /Source/Sandbox/ folder. After creating the blueprint class I can’t open the project now (using 4.11.2).

When I open the project it says “Missing Sandbox Modules. The following modules are missing or built with a different engine version: UE4editor-Sandbox.dll. Would you like to rebuild them now?”.

When I click “no”, it wonÄt open the project. When I click yes, it starts rebuilding but the aborts and says “Sandbox could not be compiled. Try rebuilding from source manually.”

Anyone knows what’s going on here? I thought it would be easier to add a c++ class to a project. Is there a way to recover my project and make it right again?

Thanks,
Florian

EDIT: My project is called “Sandbox”

How did you add the C++ Class?

You might need to generate the visual studio files and compile Development Editor to run the project in the Editor.

I often add new C++ Class’s form the Editor because it puts them in the right place and generates the header file, but it is not necessary you can do it form Visual Studio also. But, you will need to right click the project file and run generate files and compile to open it in the Editor.

You saved my day. Thanks, I had messed up my VS install.