Qt, strange warning of QNetworkSession?

I am trying to download some image from the internet using Qt's QNetworkManager, QNetworkReply and QNetworkRequest.

The downloading is working in a thread pool. And sometimes I got the following warning from Qt:

Type conversion already registered from type QSharePointer<QNetworkSession> to type QObject*

QObject::connect: Incompatible sender/receiver arguments QNetworkSessionPrivateImpl::stateChanged(QnetworkSession::State) --> QNetworkSession::stateChanged(QNetworkSession::State)

Which is quite strange. Isn't the QNetworkManager, QNetworkReply and QNetworkRequest reentrant?