When updating some of the later Dahua cameras to newer firmware, the standard methods don't always work. In this example below one of our customers was trying to update his IPC-HFW4300S cameras to newer firmware. he had to perform the procedure below to get it to work. We are posting this information just in case it can help anyone else. 

The newer ConfigTool didn't work, so he had to use the PC Config tool 1072 (old style config tool), and change the port to 3800 to get it to load. Uploading the firmware was completely unsuccessful any other way, including using my NVR with thumbdrive, New PC config tool, Mac Config tool, using the older firmware version listed below, or any other approach.