I had that happen on a ride, but it was my Garmin 500 that went bad - wouldn't read more than a few hundred feet each time I reset it, so I had 0.1 miles recorded when I got home.

As it was a route I've done before, I copied/renamed the old fit file, edited it to change the dates (in Notepad) and then went to Strava and did an 'upload from file'. It worked just fine. I just wanted the mileage, so the stats being off a bit was no big deal.