How to Fix UE5 C2230 Error: Could Not Find Class Declaration in C++ Code

Why You’re Seeing This Error

The compiler can’t find the declaration of a class you’re trying to use. This typically happens when you haven’t included the proper header file or when there’s a circular dependency issue.

Example Error Message

error C2230: could not find class declaration for 'AMyCharacter'

Solution

1. Include the necessary header: Make sure you’ve included the header file that contains the class declaration.

#include "MyCharacter.h"

2. Fix circular dependencies: Use forward declarations when appropriate.

// In HeaderA.h
class ClassB;  // Forward declaration

class ClassA
{
    ClassB* MyBInstance;  // Only using pointer, so forward declaration is enough
};

// In HeaderB.h
#include "HeaderA.h"  // Full include needed to inherit from ClassA

class ClassB : public ClassA
{
    // Implementation
};

3. Check include paths: Make sure your include paths are correct, especially for classes in different modules.
4. Generate project files: Try regenerating your Visual Studio project files.
5. Check for correct namespaces: Make sure you’re using the correct namespace if the class is in one.

// If the class is in a namespace
namespace MyGame
{
    class AMyCharacter;  // Forward declaration with namespace
}

// When using the class
MyGame::AMyCharacter* CharacterPtr;