How to upload current activity

Try a manual upload from your Garmin device to Garmin Connect Web - How Do I Manually Upload an Activity I Recorded to Garmin Connect?

If you get any message other than Import Complete, then there is a problem with the file. Attach it to this thread. We can take a look to see if it is repairable.

• Zip the file, then in a reply post Insert >> Image/video/file >> click Upload >> browse for file >> OK.
• Or upload the fit file to a reputable file sharing service, such as OneDrive, Google Drive, Dropbox, make the file public, then paste a link to the file in your post.

Easier trick that works usually: restart the watch and then sync from the phone app

Yes, as long as the activity isn't corrupt

Corrupt file won't import even on the website unless it's fixed before 

Exactly my point. A manual upload will show you the error message.