Starting with MacOS 10.14.4, Apple changed how USB devices are recognized on certain Macs. This caused a timing problem with boards that were loaded with a MakeCode program, preventing the
CPLAYBOOT drive (or other
...BOOT drive) from appearing.
To see if you need to update your bootloader, get
CPLAYBOOT to appear on your board. If you're running MakeCode, click the reset button once. If you're running CircuitPython or an Arduino program, double-click the reset button. All the NeoPixels should turn green.
CPLAYBOOT drive in the Finder and then double-click the
INFO_UF2.TXT file to see what's inside.
The bootloader version is listed in
INFO_UF2.TXT. In this example, the version is "
If the bootloader version you see is older than "v3.3.0-adafruit.10", you need to update. For instance, the bootloader above needs to be upgraded.
Download the latest version of the Circuit Playground Express bootloader updater here:
The bootloader updater will be named
update-bootloader-circuitplay_m0-v3.3.0-adafruit.10.uf2 or some later version. Drag that file from your
Downloads folder onto the
After you drag the updater onto
CPLAYBOOT, the red LED on the board will flicker as the bootloader is updated. The NeoPixels will flash and turn green again. A few seconds later,
CPLAYBOOT will reappear in the Finder. After that, you can click on
CPLAYBOOT and double-click
INFO_UF2.TXT again to confirm you've updated the bootloader.
If your Mac has already been updated to MacOS 10.14.4 and now you can't see
CPLAYBOOT in the Finder, you need to find another computer that will work. Not all upgraded Macs will fail to show
CPLAYBOOT: older ones can work. Or find a Mac that hasn't been upgraded yet. Any Windows 10 or Linux computer should work for upgrading your bootloader. Windows 7 computers will need drivers installed, but then can work.
If you don't have a Circuit Playground Express, but are using a different Adafruit board with a UF2 bootloader, the procedure is similar to what you see above. Single-click (if using MakeCode) or double-click the reset button. You'll see a drive whose name ends in
...BOOT. Check the version as above. If you need to update, download a bootloader updater for your board. Links to the latest updaters are available here in the Updating the bootloader section on the UF2 Bootloader Details page. Then drag or copy the updater .uf2 file onto your