Here is an update to my Jan 12 post. All my "FTDI232" adapters are FAKES, as they have the same serial number. Apologies to the OEM. I have also acquired at CP2102 based adapter, and it seems fine. Downloading can be performed at very high rates. The following were fine python c:\esptool\esptool.py ...

Summary What worked for me after several days of anguish was switching USB to RS323 interfaces - from FTDI232 (FT232RL), assumed legitimate - to AiThinker (CH340G) My symptoms using FTDI: flashing with esptool failed early with some variation of the following Writing at 0x00009 A fatal error occurre...