# DECLARE\_DYNAMIC\_DELEGATE\_ThreeParams() Error

**URL:** <https://forums.unrealengine.com/t/declare-dynamic-delegate-threeparams-error/448468>\
**Category:** C++\
**Tags:** error, unreal-engine, delegates, UE4, CPP, question\
**Created:** [May 6, 2019, 9:31am UTC](https://forums.unrealengine.com/t/declare-dynamic-delegate-threeparams-error/448468 "2019-05-06T09:31:24Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Bazzy2000](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Bazzy2000](https://forums.unrealengine.com/u/Bazzy2000)\
**Post date:** [May 6, 2019, 9:31am UTC](https://forums.unrealengine.com/t/declare-dynamic-delegate-threeparams-error/448468/1 "2019-05-06T09:31:24Z")

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I’m getting an error every time I try to include DECLARE\_DYNAMIC\_DELEGATE\_ThreeParams(); into my .h file. The error says “this declaration has no storage class or type specifier” and that FOnProgress is undefined. I’ve tried to include the Delegates/Delegate.h header file, but still getting the same error. I’ve also tried to regenerate my project but still didn’t fix this error. What am I doing wrong? Is it a bug?

```
#include "CoreMinimal.h"
#include "UObject/NoExportTypes.h"
#include "Http.h"
#include "Delegates/Delegate.h"
#include "Download.generated.h"

DECLARE_DYNAMIC_DELEGATE_ThreeParams(FOnProgress, const int32, BytesSent, const int32, BytesRecieved, const int32, contentLenght);
//
UCLASS()
class Download_API Downloader : public UObject
{
	GENERATED_BODY()

public:

	FOnProgress OnProgress;
};
```

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**Author:** ![Ascianous](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Ascianous](https://forums.unrealengine.com/u/Ascianous)\
**Post date:** [May 6, 2019, 11:40am UTC](https://forums.unrealengine.com/t/declare-dynamic-delegate-threeparams-error/448468/2 "2019-05-06T11:40:42Z")

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Rather than there being an error here, this feels to me like a stupid intellisense/compiliation problem. Reading around at similar problems, it seems like they all recommend the following (all in Visual Studio)

1. Switch the Solution Configuration (its one of the dropdown menus at the top, next to where you press the green start for the debugger) to any other setting
2. Recompile - this will force all of the headers to be recompiled
3. Switch back to the original setting and recompile again

If it is some intellisense or compilation error, this should resolve it. I appreciate you said you’ve already regenerated the project but, my previous experience with things like this is sometimes event that doesn’t cut it…

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**Author:** ![Bazzy2000](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Bazzy2000](https://forums.unrealengine.com/u/Bazzy2000)\
**Post date:** [May 6, 2019, 12:25pm UTC](https://forums.unrealengine.com/t/declare-dynamic-delegate-threeparams-error/448468/3 "2019-05-06T12:25:43Z")

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I did what you suggested and got it to work. Thank you!

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<div class="post-metadata">

**Author:** ![Bazzy2000](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Bazzy2000](https://forums.unrealengine.com/u/Bazzy2000)\
**Post date:** [May 6, 2019, 12:56pm UTC](https://forums.unrealengine.com/t/declare-dynamic-delegate-threeparams-error/448468/4 "2019-05-06T12:56:03Z")

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Solution:

1. Switching the Solution Configuration to any other setting. 2) Recompiling - this will force all of the headers to be recompiled. 3) Switching back to the original setting and recompiling again.

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<div class="post-metadata">

**Author:** ![Reahreic](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/reahreic/32/911691_2.png) [@Reahreic](https://forums.unrealengine.com/u/Reahreic)\
**Post date:** [June 3, 2024, 7:19pm UTC](https://forums.unrealengine.com/t/declare-dynamic-delegate-threeparams-error/448468/5 "2024-06-03T19:19:22Z")

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I get this error with `DECLARE_DYNAMIC_DELEGATE_RetVal` but regardless of what I do to the solution, including regenerating VS project files it halts all progress.