4.15 CreateSession() return array out of bound.

[KillerPenguin]

Dear all,

After we upgraded to UE4.15, the function CreateSession() crashes the engine every time it is called. It always produces “array is out of bound” error. We changed the code to comply with Shooter example and it still crash every time.

Never had any of this problem before 4.15. Anyone has any idea on how this could happen?

Best,

IOnlineSubsystem* mOnlineSubSystem = IOnlineSubsystem::Get();
if (!mOnlineSubSystem) GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, TEXT(“Error: IOnlineSubsystem failed.”));
else if (!mOnlineSubSystem->Init()) GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Yellow, TEXT(“Network Interface fail to initialized.”));
else
{
mSessionParams.SessionName = nSessionName;
mSessionParams.bIsLAN = true;
mSessionParams.bIsPresence = true;
mSessionParams.UserId = nControllerId;

	IOnlineSessionPtr mSession = mOnlineSubSystem->GetSessionInterface();
	if (mSession.IsValid() && mSessionParams.UserId.IsValid())
	{
		HostSettings = MakeShareable(new FGameSessionSettings(true, true, MaxNumPlayers));
		HostSettings->Set(SETTING_GAMEMODE, nGameType, EOnlineDataAdvertisementType::ViaOnlineService);
		HostSettings->Set(SETTING_MAPNAME, nMapName, EOnlineDataAdvertisementType::ViaOnlineService);
		HostSettings->Set(SEARCH_KEYWORDS, MatchKeyword, EOnlineDataAdvertisementType::ViaOnlineService);
		OnCreateSessionHandle = mSession->AddOnCreateSessionCompleteDelegate_Handle(OnCreateSessionCompleteDelegate);
		return mSession->CreateSession(*mSessionParams.UserId, mSessionParams.SessionName, *HostSettings);
	}

[KillerPenguin]

Lord, we found the error.

It seems that 4.15 change the way OnlineSubSystem initialized. So the mOnlineSubSystem.Init() is actually creating a zero length array which caused the error.
By removing mOnlineSubSystem->Init(). Everything is back to normal now.

[Rama]

Thanks for letting us all know @KillerPenguin!

Rama