This stuff used to work... My Windows 7 had a bunch of updates though, so that might have an impact.
Using ANT agent, I get server error during upload.
I tried using manual update instructions: https://forums.garmin.com/showthread.php?32850-Garmin-Connect-failed-due-to-server-error
However with them I get "An error occurred with your upload. Please try again." every time.
Any ideas? Using Forerunner 910XT. Ant agent 2.3.4.