"An error occurred with your upload. Please try again."
First thing I did was tried the same GPX file against other sites, and it works on all of them (gpsvisualizer.com, maplorer.com and others). I then tried three different browsers (chrome, firefox, safari) and three OS'es: Linux, Windows, Android (using the browser, not the connect app), again I got the same useless error message.
It then occurred to me that I might be able to look at the server response, to which I found:
ManualUploadPageView.js?bust=4.6.0.12:1 Wed May 02 2018 15:36:59 GMT+0100 (BST) - error uploading file Outdoor Magic Trail Half Marathon.gpx status(400)
ManualUploadPageView.js?bust=4.6.0.12:1 Wed May 02 2018 15:36:59 GMT+0100 (BST) - Failed to parse JSON (null)
Now here's the thing. GPX is in XML format ( https://en.wikipedia.org/wiki/GPS_Exchange_Format ) , so why are Garmin trying to parse JSON format?
Perhaps a developers mistake and its just mistyped in the logs.
Anyway is it possible this could be fixed? Everytime I get prepared for a big race where I will need GPS navigation I cannot upload any GPX files. I can see threads going back 2014 where this feature seems to break a lot.