Sending a Ctrl-D to the MicroPython REPL to initiate a soft reset and then immediately issuing a Ctrl-C causes the entire filesystem to be erased on the Raspberry Pi Pico board. This issue was observed on 2 separate Pico boards across the following nightly builds (the 4 latest as of 01 March 2023):

• v1.19.1-910-g4937174b4
• v1.19.1-909-g36ae5d3e8
• v1.19.1-900-gfc4c47f7b
• v1.19.1-897-g72e931832

However, the bug was not observed in the latest stable version 1.19.1.

Steps to reproduce

These steps were tested on a Linux host (Ubuntu 22.04).

First, load one of the above nightly versions of MicroPython onto a Raspberry Pi Pico board.

Next, using mpremote, install a library on the Pico’s filesystem, for example hashlib:

mpremote mip install hashlib

Then check that the library exists on the Pico’s filesystem:

mpremote fs ls /lib

This should show the hashlib folder:

ls :/lib
           0 hashlib/

Then, to send the required keystrokes (Ctrl-D followed by Ctrl-C), execute the following lines of Python on the Linux host machine to which the Pico is connected, replacing /dev/ttyACM0 with the serial port of the MicroPython REPL. This script requires pyserial.

import serial
s = serial.Serial('/dev/ttyACM0')
s.write(b'\x04') # Ctrl-D
s.write(b'\x03') # Ctrl-C
s.close()

Less precisely, the issue can also be reproduced by entering a REPL with mpremote and pressing Ctrl-D and Ctrl-C in rapid succession.

Then check the Pico’s filesystem once again:

mpremote fs ls

This should show that the lib folder and all files it contains have been removed:

ls :

This issue became evident because the visual studio code extension Pico-W-Go exhibits this behaviour when running a MicroPython file, issuing a Ctrl-D and Ctrl-C in rapid succession before running the given code. This issue has been reported on that project’s GitHub page here, suggesting it affects other nightly versions older than the 4 listed above.