I've realized that my case is the same as the one described in this post https://www.esp32.com/viewtopic.php?t=12600 . The module is pre-programmed with the AT firmware which interferes with the JTAG pins. Does this mean that we have no choice other than using a USB to serial programmer? Isn't there...

Thanks @mikemoy for your reply. True that. Here is the JTAG pinout (based on https://github.com/espressif/esp-iot-solution/blob/master/documents/_static/esp-prog/JTAG_pin.png ): 2x5 JTAG header pin number -----> ESP32 Module IO number -----------------------------------------------------------------...

I've been trying to program the ESP32-WROOM-32E and ESP-DevKitC-v4 (based on 32E) modules over JTAG (both on MacOS 10.15.4 and Windows 10) for the past two days and every single try has failed following the same error. It's worth mentioning that I erased the flash memories of these modules entirely ...