Someone can explain why this error is happening

Development Programming & Scripting
1

the .h file

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

#pragma once

#include "BehaviorTree/BTService.h"
#include "BTService_CheckforPlayer.generated.h"

/**
 * 
 */
UCLASS()
class MEUPROJETO_API UBTService_CheckforPlayer : public UBTService
{
	GENERATED_BODY()

public:
	UBTService_CheckforPlayer();

	virtual void TickNode(UBehaviorTreeComponent& OwnerComp, uint8* NodeMemory, float DeltaSeconds) override;
	
	
};


the .cpp file

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

#include "MeuProjeto.h"
#include "BTService_CheckforPlayer.h"
#include "MyAIController.h"
#include "BehaviorTree/BehaviorTree.h"
#include "BehaviorTree/BehaviorTreeComponent.h"
#include "BehaviorTree/BlackboardComponent.h"
#include "BehaviorTree/Blackboard/BlackboardKeyAllTypes.h"
#include "Enemy.h"

UBTService_CheckforPlayer::UBTService_CheckforPlayer()
{
	bCreateNodeInstance = true;
}

void UBTService_CheckforPlayer::TickNode(UBehaviorTreeComponent& OwnerComp, uint8* NodeMemory, float DeltaSeconds)
{
	AMyAIController *me = Cast<AMyAIController>(OwnerComp.GetAIOwner());

	if (me)
	{
		ACharacter *Player = Cast<ACharacter>(UGameplayStatics::GetPlayerCharacter(GetWorld(),0));
		if (Player)
		{
			OwnerComp.GetBlackboardComponent()->SetValue<UBlackboardKeyType_Object>(me->PlayerId,Player);
			//OwnerComp.GetBlackboardComponent()->SetValueAsObject("Target", Player);
		}
	}

}

and the errors:

CompilerResultsLog:Error: Error BTService_CheckforPlayer.cpp.obj : error LNK2001: unresolved external symbol “public: virtual void __cdecl IGameplayTaskOwnerInterface::OnGameplayTaskActivated(class UGameplayTask &)” (?OnGameplayTaskActivated@IGameplayTaskOwnerInterface@@UEAAXAEAVUGameplayTask@@@Z)

CompilerResultsLog:Error: Error MeuProjeto.generated.cpp.obj : error LNK2001: unresolved external symbol “public: virtual void __cdecl IGameplayTaskOwnerInterface::OnGameplayTaskActivated(class UGameplayTask &)” (?OnGameplayTaskActivated@IGameplayTaskOwnerInterface@@UEAAXAEAVUGameplayTask@@@Z)

CompilerResultsLog:Error: Error BTService_CheckforPlayer.cpp.obj : error LNK2001: unresolved external symbol “public: virtual void __cdecl IGameplayTaskOwnerInterface::OnGameplayTaskDeactivated(class UGameplayTask &)” (?OnGameplayTaskDeactivated@IGameplayTaskOwnerInterface@@UEAAXAEAVUGameplayTask@@@Z)

CompilerResultsLog:Error: Error MeuProjeto.generated.cpp.obj : error LNK2001: unresolved external symbol “public: virtual void __cdecl IGameplayTaskOwnerInterface::OnGameplayTaskDeactivated(class UGameplayTask &)” (?OnGameplayTaskDeactivated@IGameplayTaskOwnerInterface@@UEAAXAEAVUGameplayTask@@@Z)

CompilerResultsLog:Error: Error C:\Users\marco\OneDrive\Documentos\Unreal Projects\MeuProjeto\Binaries\Win64\UE4Editor-MeuProjeto-4343.dll : fatal error LNK1120: 2 unresolved externals

2

This is a linker error. Your code knows what function should be called (IGameplayTaskOwnerInterface::OnGameplayTaskDeactivated) but can’t find the implementation of that function. This function is in the GameplayTasks module, so in your “…Build.cs” file, you need to add “GameplayTasks” to PrivateDependencyModuleNames or PublicDependencyModuleNames.