Adding Userwidget classes causes compile errors

Development Programming & Scripting UI
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1

I have been migrating my old 4.7.6 project to 4.8.1 today and part of that is a simple minimap I made using a custom class based on UMG. However, when I add a class extended from the UserWidget class, I suddenly get compile errors from SlateWrapperTypes.h and a bunch of other UI related classes. Classes at the moment don’t have content apart from the default Unreal generated content. I wanted to start out with empty classes before I start adding content, to make sure any errors I get are not a direct result of my code (good thing I did).

I have made sure to add “UMG”, “Slate”, “SlateCore” to the build file (in the addrange bit), so I am not sure what exactly is going wrong here.

The error in question (I only post the first 5 out of a whole washlist of errors. I reckon they share the same core issue);

Error 2 error C2079: ‘FEventReply::NativeReply’ uses undefined class ‘FReply’ E:\Game Development\Unreal4\Source\UnrealEngine 4.8.1\Engine\Source\Runtime\UMG\Public\Components\SlateWrapperTypes.h 58 1 ActionGamePrototype

Error 3 error C2027: use of undefined type ‘FReply’ E:\Game Development\Unreal4\Source\UnrealEngine 4.8.1\Engine\Source\Runtime\UMG\Public\Components\SlateWrapperTypes.h 53 1 ActionGamePrototype

Error 4 error C3861: ‘Handled’: identifier not found E:\Game Development\Unreal4\Source\UnrealEngine 4.8.1\Engine\Source\Runtime\UMG\Public\Components\SlateWrapperTypes.h 53 1 ActionGamePrototype

Error 5 error C3861: ‘Unhandled’: identifier not found E:\Game Development\Unreal4\Source\UnrealEngine 4.8.1\Engine\Source\Runtime\UMG\Public\Components\SlateWrapperTypes.h 53 1 ActionGamePrototype

Error 6 error C2146: syntax error : missing ‘;’ before identifier ‘FGetCheckBoxState_DelegateWrapper’ E:\Game Development\Unreal4\Source\UnrealEngine 4.8.1\Engine\Intermediate\Build\Win64\UE4Editor\Inc\UMG\Widget.generated.h 33 1 ActionGamePrototype

2

Okay nevermind, I made a stupid mistake. In transferring to the new version, I completely forgot that if you want to extend from the userwidget class, on top of adding to the build class, you also need to add

#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”

to your project header file.

3

Well I did the includes but it still does not compile.
I have 250+ errors about UserWidget.h

I’m doing it in Third Person Example C++ 4.8.1

Did someone find a fix? Please help!

4

Did you add “UMG”, “Slate”, “SlateCore” to the “PublicDependencyModuleNames.AddRange” thingy in your .Build.cs file?

5

Thanks a lot for getting back to me! I’m being stupid and included
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”
in the wrong place. now everything works fine.

6

Where in your project header did you add this? I’m having the same problem

7

Just kidding, it was literally just “MyProjectName”.h, I feel silly. Maybe my issue was a little different, looked like I was using “EngineMinimal.h” instead of “Engine.h”. Adding those line also worked though.

8

Can someone please tell me where exactly is it written that you need to include all those headers in addition to UserWidget.h ?
I literally spent hours trying to solve this problem and did not find one piece of documentation that would mention that.

9

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10

As I tried, only UMG.h is needed and indeed it must be placed in PCH (project header).
I will not add a header in PCH until it is really needed, say, until the next time I meet another compile error.

11

As I tried, only UMG.h is needed and indeed it must be placed in PCH (project header).
I will not add a header in PCH until it is really needed, say, until the next time I meet another compile error.