ArcGIS applications return a "Runtime Error R6034" when trying to load Python _ctypes.pyd or any other function tools (DLL) that load CRT9 without a manifest dependency entry.
General patch for 10.4 and 10.4.1 has been released to address this issue. <a href="http://support.esri.com/download/7391" target="_blank">http://support.esri.com/download/7391</a>