What It Means & How to Fix It

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🧠 Why You’re Seeing This Error

C4430 means you tried to declare something (like a variable or function) without giving it a type, and the compiler defaulted to int — which isn’t allowed in modern C++.

In UE5, this is often caused by:

• Missing the type when declaring a variable or function
• Misspelled or undeclared types (especially custom structs or engine classes)
• Forgetting to include the type’s header file

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💥 Example Error Message

error C4430: missing type specifier - int assumed. Note: C++ does not support default-int

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🛠️ Example Code

UPROPERTY()
Health; // ❌ C4430: Missing type

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✅ How to Fix C4430 in UE5 – Step-by-Step

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✔️ 1. Declare a Type for Every Variable

Fix:

UPROPERTY()
int32 Health; // ✅

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✔️ 2. Check for Missing Headers for Custom Types

If you’re using a custom struct, class, or UE type (FMyStruct, UMyComponent*, etc.), make sure you’ve included the right file.

Wrong:

FMyStruct Data; // ❌ Missing include

Fix:

#include "MyStruct.h"
FMyStruct Data; // ✅

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✔️ 3. Don’t Declare Functions Without Return Types

Wrong:

DoSomething(); // ❌

Fix:

void DoSomething(); // ✅

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✅ Summary: How to Fix C4430 in UE5

Cause	Fix Example
Missing variable type	Declare it: int32 Value;
Typo or unknown type name	Fix spelling or include required header
Missing return type on function	Add void, int32, etc.