I have been following along with the examples for micropython and ESP32.
I copied the boot.py code and the main.py code but when I try to download and run I get result below.
>>> Ready to download this file,please wait! ..... download ok os.listdir('.') Traceback (most recent call last): File "<stdin>", line 1, in <module> NameError: name 'os' isn't defined >>> reflush tree false
A similar issue was discussed here: https://rntlab.com/question/reflush-tree-false-error/
I hope this helps.