🧠 Why You’re Seeing This Warning

LNK4217 is a linker warning (not an error) that means:

A symbol (like a variable or function) was defined in your local module, but is also being imported from another module.

This is usually caused by inconsistent usage of __declspec(dllexport) and __declspec(dllimport), which Unreal handles through its MYMODULE_API macros.

In UE5, this shows up when:

• You define a UCLASS, USTRUCT, or UENUM without using your module’s API macro (e.g., MYGAME_API)
• You forget to use MYMODULE_API in a public class or struct
• You create plugins or modules with cross-referenced headers, and the symbols are seen as both “local” and “imported”

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💥 Example Warning Message

warning LNK4217: locally defined symbol class "FMyStruct" imported in function ...

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🛠️ Example Code

// MyStruct.h

USTRUCT()
struct FMyStruct // ❌ No export macro
{
    GENERATED_BODY()
    int32 Value;
};

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✅ How to Fix LNK4217 in UE5 – Step-by-Step

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✔️ 1. Use the Correct MODULE_API Macro in All Public Types

Every public USTRUCT, UCLASS, or UENUM should be declared like this:

// Assuming your module is named MyGame
USTRUCT(BlueprintType)
struct MYGAME_API FMyStruct // ✅ Use export macro
{
    GENERATED_BODY()
    int32 Value;
};

This tells UE5 (and the linker) to handle export/import behavior consistently across modules.

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✔️ 2. Make Sure Your .Build.cs File Defines the Module Properly

Your *.Build.cs file should contain the correct PublicDependencyModuleNames so types from other modules are handled cleanly:

csharpCopyEditPublicDependencyModuleNames.AddRange(new string[] { "Core", "Engine", "MyOtherModule" });

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✔️ 3. Don’t Worry — It’s a Warning, Not an Error

LNK4217 won’t break your build, but it can cause symbol conflicts or larger EXE sizes if left unchecked, especially in multi-module or plugin-heavy projects.

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✔️ 4. Use #pragma warning(disable : 4217) Sparingly

If the warning is spamming your build log and you can’t fix the root cause immediately, you can suppress it temporarily:

#pragma warning(disable : 4217)

But this should never be your first option.

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✅ Summary: How to Fix LNK4217 in UE5

Cause	Fix Example
Missing API macro in USTRUCT/UCLASS	Use MYMODULE_API in public type declarations
Type used across multiple modules	Ensure PublicDependencyModuleNames includes dependencies
Mixed import/export handling	Consistently apply API macros across modules
Temporary suppression	Use #pragma warning(disable: 4217) only if necessary