I didn't know this trick. I recreated the fs, and this resolved the "corrupted dir" message at startup. Just in case, to make sure this wasn't a glitch, I reuploaded the latest firmware; the error message is here again. Well, not big issue as now I know how to fix this.

Everything else I tried so far works properly.

I have 2 modules Wemos' W600 at hands that I can test (other ones are identical). I erased and re-uploaded the latest firmware, this is what I got:

>>> import os;os.statvfs("")
(4096, 4096, 68, 65, 65, 0, 0, 0, 0, 255)

So, 278528 bytes total, 266240 bytes free.

Just out of curiosity, I recreated the fs as you suggested above, I got:

>>> import os;os.statvfs("")
(4096, 4096, 68, 66, 66, 0, 0, 0, 0, 255)

A bit more free space, 266240 bytes. I believe this is because after recreating the fs, 2 files were deleted (boot.py, main.py).

As soon as the fs has been created, there is no error message on corrupted dir anymore. Maybe my modules are somehow different / counterfeit? When buying something on AliExpress, you never know what will come.

Well.. Why I wanted to update to MP v1.20 is "mip". I just wanted to see how this work. But, it doesn't work at all:

>>> import mip
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "mip/__init__.py", line 1, in <module>
  File "urequests.py", line 1, in <module>
ImportError: no module named 'usocket'

I will try to add missing Python files.

Anyway, it seems the new firmware works just fine with the network; that's the only critical part for me. Other things like "mip" I can test on ESP8266 or ESP32 modules.

I have tested the latest firmware. mip works as expected. I had to add "/lib" to the system path before installing packages. I tried to install the standard module and a custom one; both methods work:

import mip
import network_utils as nu # A module to work with Wi-Fi.

sys.path.append("/lib")
net = nu.connect(...)
if net:
    mip.install("ssd1306")
    mip.install("https://raw.githubusercontent.com/robert-hh/SH1106/master/sh1106.py") 

MicroPython v1.20.0-483-g688bb2449 on 2023-09-09; Wemos W600 Pico with W600-B8
Type "help()" for more information.
connecting in progress (code 1)
connecting in progress (code 1)
got IP (code 5)
Installing ssd1306 (latest) from https://micropython.org/pi/v2 to /lib
Copying: /lib/ssd1306.mpy
Done
Downloading https://raw.githubusercontent.com/robert-hh/SH1106/master/sh1106.py to /lib
Copying: /lib/sh1106.py
Done

Great. I don't know yet where I would need mip, just didn't think if it would be useful for me, but I am glad that it works (and yet another test for the network subsystem, too).

Robert, thank you for these fixes! I am always ready to test and try new firmware you prepared.

(I can't rebuild the firmware on my own at the moment. I have tons of tool chains for various MCU installed on Ubuntu 18.04, and it seems there was some conflict when I added gcc you recommended for WM_SDK. I don't want to touch this till I complete my project for STM32F103 MCU related to hacks for hoverboard firmware. I should use a VM for experiments, but I am too lazy to deal with this...)

Thanks for the hint. I extended the firmware to include /lib into sys.path and to create /lib with a new file system. That's done in scripts/_boot.py, which runs at every boot event.

Edit: b.t.w., the command line for creating the firmware is:

make V=s SECBOOT=1 CODESIZE=0xa8000 BOARD=WEMOS_W600

You could try to reduce CODESIZE a little bit, if you need more space in the file system. 0xa4000 should work as well, gaining 16k. And you can set SECBOOT=0, which adds another 56k to the file system.

The uypsh module from micrpython-lib is embedded as frozen module. That add a few useful IX like commands like ls, cat, mkdir, rmdir, rm ... Start it with from upysh import *.