18k errors when extending AnimInstance?

I created a new C++ class using animinstance as the parent and it doesn’t build. I get 18k errors, most complaining about "cannot open source file “UBT_COMPILED_PLATFORM/UBT_COMPILED_PLATFORM blah blah blah.h” I’ve followed several tutorials that all say to do this to be able to set animation blueprint variables from c++. Is there some other step I’m missing or is something else going on?

Check to see if your Solution is set as “Development Editor” and your Solution platform is set as “Win64”.

Also, you might need to have “AnimationCore” module in your public dependencies.

The solution was set to Development Editor and the platform was Win64. I’m using VS2017. I’m not sure how I can check to see if AnimationCore is in public dependencies or add it if it’s not. I see an External Dependencies folder, but that doesn’t have AnimationCore in it.

You should see a file in your Source folder, named after your project and ends with “.Target.cs”. Inside you’ll find something like this:

ExtraModuleNames.AddRange( new string] { "YourProjectName" } );

Change it to

ExtraModuleNames.AddRange( new string] { "YourProjectName", "AnimationCore" } );

Rebuild, see if that helps.