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 download 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 downloading 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?"