FAIL.TXT / Flash Failed
BBC Micro:bit
Severity:What Does This Error Mean?
A FAIL.TXT file on your Micro:bit's USB drive means the .hex file transfer failed and the program did not flash correctly. Open FAIL.TXT to read the error code, then reflash by dragging the .hex file again — slowly and from a USB 2.0 port.
Affected Models
- BBC Micro:bit V1
- BBC Micro:bit V2
Common Causes
- USB 3.0 port causing transfer speed issues with the Micro:bit's USB mass storage
- Corrupted or incomplete .hex file downloaded from MakeCode or Python editor
- Dragging the file to the wrong location on the drive
- Micro:bit firmware (interface firmware) is outdated
- Antivirus scanning and modifying the .hex during transfer