Further to my Post, problem solved.
I must upload the sketch using "Upload", NOT "Upload Using Programmer".
With "Upload", everything works OK.

I am trying to program the ESP32 Dev Module using Arduino IDE (v 1.8.9), on Windows 10. Using Board Manager, I have installed "esp32 by Espressif Systems" I'm starting with an absolute minimum sketch that does nothing, as follows: void setup() { } void loop() { } I have selected board “ESP32 Dev Mod...