Garmin won't sync - Forerunner 310XT activity upload solution

My 310XT was not syncing. In fact, I have two of them, and none of them would upload new activities. I could add the device to Garmin Express, and it would recognize and pair properly -- but it simply would not transfer any data to Garmin Connect.

By the way, I'm posting this because I am guessing many runners also have the 301XT.

I'm on Windows 7. Obviously for Mac this info doesn't apply.

I tried all the standard procedures: Making sure Garmin Express was up to date. Deleting the "Devices" folder in the AppData folder. If you do a lot of searches, you'll eventually end up at the same Garmin FAQ page that gives you all those tips.

I even did a factory reset of the watch -- which of course deletes all saved activities. (Again, you can find out how to do a reset if you search for it online.)

The problem is, the FAQ topic page on Garmin is wrong in telling you what folder to delete.

I called tech support, and the rep had me visit this location instead:

"C:\ProgramData\Garmin\CoreService\Devices".

Once there, open up the folder matching your device's Unit ID, and delete the "Sync" folder inside.

(If you have multiple devices, find Unit ID under the "About Forerunner" menu item and look for the folder name that matches the Unit ID)

FYI: The Sync folder is a temporary location for data while it transfers from your watch to Garmin Express. It doesn't store any data permanently.

Anyway, that did the trick. Hope this helps someone else.