This looks similar to the problem introduced by Windows 10 Update (July 10th Update) - and subsequently fixed by the 16th July update
Aug 14, 2018 21:40:41.048 [9552] ERROR - [Transcoder] [dash @ 024ba9c0] Unable to open http://127.0.0.1:32400/video/:/transcode/session/7q7floeh43mned7vlh1rx1le/8adc9790-5b64-4cc5-8e5b-2b208fef95e4/manifest for writing
Aug 14, 2018 21:40:41.063 [13732] ERROR - [Transcoder] av_interleaved_write_frame(): Unknown error
See [Windows 10 Update KB4338819 issue] Conversion Failed. The transcoder exited due to an error and the solution linked to the first post
You will need to check for updates and may need a number of restarts to pick the later windows updates
Details on that forum thread
