Hey @Sebastiensmith,

Thanks for writing in here and apologies for any delay in responding to your request.

Unfortunately this could be happening because the watch is attempting to write several invalid/bad timestamps into the FIT file near the end of the activity. Despite the bulk of the activity being correct, even just one bad timestamp will render the activity invalid for upload to our system due to parsing issues. 

While recovery of the activity in question is not possible in this situation, moving forward you do have a couple of good options for getting credit for your efforts.

1. Manual Activity: When GPS data didn't record or isn't available through a friend

You can create a manual activity to account for the lost mileage - although this won't count toward Strava Challenge Leaderboard (they may count toward challenge progress on some Strava challenges) and won't match to any segments.

For more information on how this feature works, please see the help articles for the web, iPhone, or Android.

2. Activity sharing: If you were with a friend who recorded the activity with GPS

For more information on how this feature works please see our Help Center article.