Same here. I've been using Garmin Connect for "ages", but suddenly the 310XT .gpx files won't upload. (And I'm using Linux, so I can't use the Garmin SW made for M$ Windows....)
Quick update to this problem;
In FAQ some very friendly user @TRAVIS.VITEK told me to try uploading my files via http://home.comcast.net/~travis.vitek/upload.html this link and it have actually worked! Still I hope that GC wil fix this problem so that we cann use upload button in future.
Try to follow the four-step instructions. Even if you press the Submit Query button and get some piece of code in return that ends with the word "failure", do not be fooled. Check you GC dashboard, the file you wanted to upload should be there.
Try to follow the four-step instructions. Even if you press the Submit Query button and get some piece of code in return that ends with the word "failure", do not be fooled. Check you GC dashboard, the file you wanted to upload should be there.