Between 10.0.0-alpha.4 and alpha.5, this code.py started failing on SAMD51, specifically PyPortal:

import board
import sdcardio
import storage
import time

spi = board.SPI()
cs = board.SD_CS

print("mounting sd card...")
sdcard = sdcardio.SDCard(spi, cs)
vfs = storage.VfsFat(sdcard)
storage.mount(vfs, "/sd")
print("sd card mounted")

while True:
    print("sleep 1")
    time.sleep(1)

On Linux: It prints sleep 1 once and then the USB connection hangs up. Then it reconnects after tens of seconds, , prints "sleep 1 again once, then disconnects again, and then starts printingsleep 1` regularly on the display, but there is no USB connection.

On Window 11 and macos 26.0: Similar behavior, but it prints sleep 1 much more slowly, with many seconds in between.

I'm testing on other ports as well. On an RP2040 Metro it does not crash, but often I get "no SD card", and it requires a hard power-cycle. Also on RP2040, a drive for the SD card appears on Linux, but is not mounted.

#10351 is a possibly relevant PR that was included in alpha.5. I think this all has to do with problems with auto-USB-presentation of secondary mounts. EDIT: #10351 prevented it from mounting at all, so I think it's something else.

Metro RP2350 acts like a Fruit Jam and seems to work OK, maybe because it always presents something?