Why is my MakeCode program/.hex file not downloading onto my micro:bit?

There are a few reasons why your .hex file (the type of file that is created in MakeCode) may not download to your micro:bit. A “.hex” file is the only file type that a micro:bit will read. Whether you are downloading your .hex file directly from MakeCode, or you are downloading a custom .hex file (like the BitFirmware.hex required for bluetooth connection) from our website, confirming that the .hex file is actually copied onto your micro:bit is important. 

Note: While micro:bit may appear in your File Explorer (Windows/Chromebooks) or on your Desktop (Macs) as a drive, micro:bits do not behave like drives. When a .hex file is “copied” onto the micro:bit, that file will begin to automatically run as a program. The .hex file will not show up in the micro:bit as it would in your typical drive.

Here are some reasons why your .hex file may not be downloaded to your micro:bit:

1. Your computer is not connecting to your micro:bit. Check to see if your micro:bit is showing up as a drive in your file explorer (Windows/Chromebook) or on your desktop (Mac). If not, then you will want to see our article titled, "Why is my micro:bit not showing up on my computer?"
2. Your .hex file is downloading somewhere other than your micro:bit. It is possible that the .hex file is downloading to your computer, but it is not going directly to the micro:bit (see video below). If you would like to change your download settings, visit out setup module for MakeCode and Hummingbird Bit.
3. You have a hardware or coding issue. It is possible that the file is making it onto the micro:bit, but due to a hardware issue or a coding issue, the code is not behaving as expected. Do an icon test to make sure the code is making it onto your micro:bit. 
4. Your micro:bit needs a firmware update. When you copy or download the .hex file to the micro:bit, the yellow light on the back of the micro:bit should flash. If the light is not flashing, your firmware may need to be updated. Learn more about updating your micro:bit firmware through our article, "How do I update my micro:bit firmware?"
   
5. You are using MacOS 13 or Chromebook. There are known bugs regarding .hex file downloading and these devices. See more information regarding these our article titled, "Why is my MakeCode program/.hex file not downloading onto my micro:bit? (Chromebook and MacOS 13 specific)"