Recently I've done firmware update on my two old Canon EOS cameras using the same SD card, specifically, EOS 7D and EOS M3. I did it to M3 first, then 7D. But the update failed on 7D due to this error: "Update file cannot be found. Please check the memory card and reload the battery and try again."
There are two (2) ways to fix this.
- Reformat the SD card before copying the firmware file into it for firmware update if you don't mind losing all files.
- Simply remove or temporally save all DCIM\CANONMSC\*.CTG file(s) in the SD card to someplace else before firmware update.
I did it with the second approach. As soon as the camera detected the firmware file, the update went smoothly.