unable to flash micropython to esp 32: open serial error

issue: unable to flash micropython to esp 32: open serial error, please try again. hope to connect internet and try again.

pretty new to micropython - want to flash micropython to esp 32 ( resp 8266) board.

cf this docs: https://maker.pro/esp8266/tutorial/using-micropython-on-an-esp8266-with-upycraft

getting this errors all the time.

open serial error, please try again. hope to connect internet and try again. current version only open py txt json ini file. hope to connect internet and try again. hope to connect internet and try again.

i run Win 7

the hardware:

a. Joy-IT-Node MCU ESP8266

.. and besides that i also tried it with the following

b. ESP32-T Development Board CP2102 with Espressif ESP-WROOM-32 IoT WLAN & BLE Modul

yes: i have installed the > CP210x_Universal_Windows_Driver.zip

by the way: i could try to do all that on a linux machine. - on a MX-Linux-Sytem

any idea;

many thanks for any and all help in advance.