RE: Can't flash XIAO nrf52840

Simonr — Tue, 01 Apr 2025 09:10:15 GMT

Did you do the correct steps to put the XIAO into bootloader mode? "double tap the reset button to the left of the USB connector". We're not using UF2 flashing a lot, but I found this page on the Adafruit blog regarding UF2 on Mac: https://blog.adafruit.com/2022/10/31/uploading-uf2-files-with-macos-13-0-ventura-apple-microbit_edu-raspberry_pi-circuitpython/

Also from this post it says "If you're using MakeCode on a Mac, you need to make sure to upload the bootloader to avoid a serious problem with newer versions of MacOS. See instructions and more details here."

I tried to look around for an explanation on error code -36 but couldn't find anything, so I suggest you reach out to Adafruit support if you're not able to get the device flashing with UF2. Our suggestion would be to get a J-Link debugger or nRF52 series DK to use as a debugger/flashing device on your end as that's better for actual development. The UF2 bootloader is better for just flashing AFAIK.

Best regards,

Simon