macOS Sonoma: Problems Writing to CIRCUITPY

Apple macOS 14.x, known as Sonoma, takes many seconds to complete writes to small FAT drives, especially those 8MB or smaller. This can cause errors when writing to CircuitPython CIRCUITPY drives. When CircuitPython autoreload is enabled, you may see:

    OSError: [Errno 5] Input/output error

in the REPL output.

One workaround to this problem is to wait for the write to complete, but this can take tens of seconds. If you press the reset button or power-cycle the board before the write is complete, CIRCUITPY will be corrupted.

A better workaround is remount the CIRCUITPY drive after it is automatically mounted. This fixes the problem, for unknown reasons.

You can also consider downgrading back to macOS 13, Ventura, if that works for you.

Further information on this problem, including a shell script to do the remounting is available here, in the Welcome to Circuit Python Learn Guide, in the Troubleshooting section.

This problem is being tracked as an issue in the circuitpython repo in GitHub. If this problem affects your work, we encourage you to report the problem to Apple, using Apple’s Feedback tool.