Description

If a pawn in the level is using a custom AI Controller that sets the AIPerceptionComponent in code, the editor will crash on PIE after a hot reload.

CrashReporter:
[Link Removed]

Steps to Reproduce

1. Open UE4Editor
2. Add Class based on AIController (MyAIController), AISenseConfig (MyAISenseConfig), and AISense (MyAISense)
3. In Visual studio setup files as follows:
a. MyAIController.h

#pragma once
#include "AIController.h"
#include "Perception/AISense.h"
#include "MyAISenseConfig.h"
#include "MyAIController.generated.h"
UCLASS()
class AMyAIController : public AAIController
{
	GENERATED_BODY()
	AMyAIController(const FObjectInitializer& OI);
	UMyAISenseConfig* SenseConfig;
};

b. MyAIController.cpp

#include "[ProjectName].h"
#include "Perception/AIPerceptionComponent.h"
#include "MyAIController.h"
AMyAIController::AMyAIController(const FObjectInitializer& OI) : Super(OI)
{
	SetPerceptionComponent(*OI.CreateDefaultSubobject<UAIPerceptionComponent>(this, TEXT("PerceptionComponent")));
	this->SenseConfig = OI.CreateDefaultSubobject<UMyAISenseConfig>(this, TEXT("MyAISenseConfigs"));
	GetPerceptionComponent()->ConfigureSense(*this->SenseConfig);
}

c. MyAISenseConfig:

#pragma once
#include "Perception/AISenseConfig.h"
#include "MyAISense.h"
#include "MyAISenseConfig.generated.h"
UCLASS()
class UMyAISenseConfig : public UAISenseConfig
{
	GENERATED_BODY()
public:
	virtual TSubclassOf<UAISense> GetSenseImplementation() const override { return UMyAISense::StaticClass(); }
};

4. Compile the code
5. Create blueprint based on Pawn
6. In Blueprint defaults, set AI Controller Class to MyAIController
7. PIE / exit PIE
8. Make a small change to the project code (and/remove a character) and compile to force a hot reload
9. PIE after hot reload

Result:
Editor will crash after the hot reload

Callstack
MachineId:9FA88CA44B7C623122B0039D6C8BA1B0
EpicAccountId:c807849e05a0413d99e379f2802cae9c

Access violation - code c0000005 (first/second chance not available)

""

UE4Editor_AIModule!UAIPerceptionSystem::StartPlay() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\aimodule\private\perception\aiperceptionsystem.cpp:500]
UE4Editor_Engine!UGameInstance::StartPIEGameInstance() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\engine\private\gameinstance.cpp:273]
UE4Editor_UnrealEd!UEditorEngine::CreatePIEGameInstance() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\playlevel.cpp:3137]
UE4Editor_UnrealEd!UEditorEngine::PlayInEditor() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\playlevel.cpp:2385]
UE4Editor_UnrealEd!UEditorEngine::StartQueuedPlayMapRequest() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\playlevel.cpp:1066]
UE4Editor_UnrealEd!UEditorEngine::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\editorengine.cpp:1244]
UE4Editor_UnrealEd!UUnrealEdEngine::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\editor\unrealed\private\unrealedengine.cpp:366]
UE4Editor!FEngineLoop::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\launch\private\launchengineloop.cpp:2428]
UE4Editor!GuardedMain() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\launch\private\launch.cpp:142]
UE4Editor!GuardedMainWrapper() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.9\engine\source\runtime\launch\private\windows\launchwindows.cpp:200]

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Fixed
ComponentUE - AI
Affects Versions4.9.1
Target Fix4.10
Fix Commit2702997
Release Commit2702987
CreatedSep 29, 2015
ResolvedOct 1, 2015
UpdatedApr 27, 2018
View Jira Issue