I have an Edge 520 and it will not sync using Garmin Express. I just get the error above.
I thought I needed a firmware update but I install every available firmware update and nothing changes
I have tried uninstalling Garmin Express and reinstalling. (Delete all Application Data)
I have removed and re-added my Edge a few times
I have removed all the activities and segments on my Garmin
I have checked the log files and there is no useful information there.
Still no luck, any other advice?