Exception using Oauth2Client.cpp in /samples

[cjhkeep]

Trying to run Oauth2Client.cpp (in master/Release/samples),I meet a http_exception.

It can Opening browser in URI,and return the 'ok.'.But can't get the Authorization Grant(code).

https://github.com/cjhkeep/photo/blob/master/redirect.png

in ppltasks.h

 struct _ExceptionHolder
    {
    private:
        _CRTIMP2 void __thiscall ReportUnhandledError();

    public:
        explicit _ExceptionHolder(const std::exception_ptr& _E, const _TaskCreationCallstack &_stackTrace) :
        _M_exceptionObserved(0), _M_stdException(_E), _M_stackTrace(_stackTrace)
        {
        }

        __declspec(noinline)
        ~_ExceptionHolder()
        {
            if (_M_exceptionObserved == 0)
            {
                // If you are trapped here, it means an exception thrown in task chain didn't get handled.
                // Please add task-based continuation to handle all exceptions coming from tasks.
                // this->_M_stackTrace keeps the creation callstack of the task generates this exception.
                _REPORT_PPLTASK_UNOBSERVED_EXCEPTION();//**exception here**   
            }
        }

I try to change the para of m_oauth2_config in dropbox_session_sample ,but 

it seems no works,but I still think the problem in here. Wondering if someone could
advise me on what is wrong. Thanks.