I'm very ashamed that the reason was very very simple... Instead of following:
catch (Exception ex)
{
_reply.Error = "Error: " + ex.Message;
if (_client.InnerChannel.State == CommunicationState.Faulted) _client = new WCFPersonClient("WSHttpBinding_IWCFPerson"); //recreate the failed channel
}
I had actually following code:
catch (Exception ex)
{
_reply.Error = "Error: " + ex.Message + "; " + ex.InnerException.Message;
if (_client.InnerChannel.State == CommunicationState.Faulted) _client = new WCFPersonClient("WSHttpBinding_IWCFPerson"); //recreate the failed channel
}
and it turns out that ex.InnerException
was null
which caused the NullPointerException
...