UUserWidget incomplete type is not allowed

Development Programming & Scripting C++
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1

I have been following a tutorial about how to make a UMG widget into code.

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I have run into many problems when trying to use this code. First, I have an incomplete type error on my UUserWidget. Second, this incomplete type error cascades down throughout my code. I have tried to find any workarounds but I have not found any. I need to find a workaround for the UUserWidget problem.

// Fill out your copyright notice in the Description page of Project Settings.

#pragma once

#include "Runtime/UMG/Public/Blueprint/UserWidget.h"
#include "MainMenuBP.generated.h"

/**
 * 
 */
UCLASS()
class MAINMENUCODE_API UMainMenuBP : public UUserWidget
{
	GENERATED_BODY()

public:
	UMainMenuBP(const FObjectInitializer& ObjectInitializer);

	UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = MainMenu)
	TSubclassOf<UUserWidget> WidgetTemplate;

	UPROPERTY()
	UUserWidget* WidgetInstance;
};

The error is found in the first line of the class.

class MAINMENUCODE_API UMainMenuBP : public UUserWidget

2

Try this:

#pragma once
 
#include "Runtime/UMG/Public/UMG.h"
#include "Runtime/UMG/Public/UMGStyle.h"
#include "Runtime/UMG/Public/Slate/SObjectWidget.h"
#include "Runtime/UMG/Public/IUMGModule.h"
#include "Runtime/UMG/Public/Blueprint/UserWidget.h"
#include "MainMenuBP.generated.h"
 
 /**
  */
 UCLASS()
 class UMainMenuBP : public UUserWidget
 {
     GENERATED_BODY()
 
 public:
 
     UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = MainMenu)
     TSubclassOf<UUserWidget> WidgetTemplate;
 
     UPROPERTY()
     UUserWidget* WidgetInstance;
 };
3

“IncompleteType” errors mean you’re forward declaring a class and the compiler needs the class’s full definition. In this case, a header you’re including is likely forward declaring a class.

I had a similar problem with UUserWidget and just added all of these includes:

#include "Runtime/UMG/Public/UMG.h"
#include "Runtime/UMG/Public/UMGStyle.h"
#include "Runtime/UMG/Public/Slate/SObjectWidget.h"
#include "Runtime/UMG/Public/IUMGModule.h"
#include "Runtime/UMG/Public/Blueprint/UserWidget.h"

and it fixed the problem.

1 Like
4

I tried the solutions presented, but the error persists. Could it be that I’m using 4.6.1? Has UUserWidget gone private?

5

Can you update your question with your new header file and the exact errors you’re getting?

6

// Fill out your copyright notice in the Description page of Project Settings.

#pragma once

#include "Runtime/UMG/Public/UMG.h"
#include "Runtime/UMG/Public/UMGStyle.h"
#include "Runtime/UMG/Public/Slate/SObjectWidget.h"
#include "Runtime/UMG/Public/IUMGModule.h"
#include "Runtime/UMG/Public/Blueprint/UserWidget.h"
#include "MainMenuBP.generated.h"

/**
 * 
 */
UCLASS()
class MAINMENUCODE_API UMainMenuBP : public UUserWidget
{
public:
	GENERATED_BODY()

	UMainMenuBP(const FObjectInitializer& ObjectInitializer);

	UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = MainMenu)
	TSubclassOf<UUserWidget> WidgetTemplate;

	UPROPERTY()
	UUserWidget* WidgetInstance;
};

Errors on this page.

class UUserWidget
Error: incomplete type not allowed

found on line:
class MAINMENUCODE_API UMainMenuBP : public UUserWidget
under
UUserWidget

Thanks again for the help.

7

I fixed it. The answer was that initially when I created the class I used something other than UserWidget to automatically create the class. I guess when the class got automatically created that more was going on behind the scenes than anticipated. Once I created a new class with a UserWidget as the class then all the problems disappeared. Once again, I would like to thank you guys for the quick response and thank you for the help.