Repeated reboots while saving an activity

Hi, happen to myself today for a half marathon race.

Tried at least 5-6 times with no luck, everytime rebooted. Eventualy after I arrived home, and tried again and fortunately it saved.

I have exactly the same happening to me. And not only after the activity is saved but sometimes even when it's stopped/paused and I accidentally press Up/Down button - this is even worse because the activity is truncated to end of last lap after restart.

Over the weekend I experienced several reboots when trying to save or discard hiking activities on my 945. These activities took place between 5,000ft and 9,000ft. After I came home to sea level, I recorded a short cycling activity and the watch would reboot every time I tried to save it. Based on some comments here, I thought the reboots might be related to the change in elevation between activities. I set my cycling activity to "Resume Later" and looked at my PulseOx screen. It showed that I descended from 6,000ft to sea level (correct), then, about the time I started the cycling activity it showed me going back up to 6,000ft (incorrect). I started the cycling activity before I got a GPS lock, so perhaps it used the GPS coordinates from my last hike to put me at a higher elevation. As I was looking at the PulseOx screen, it measured my PulseOx and it corrected my current elevation back to sea level. After this I went back into the cycling activity and was able to save it without issue. 

Maybe it's a coincidence that the activity saved after I went into the PulseOx screen, but I had tried saving the activity at least 5 or 6 times unsuccessfully before that. I'm using the 2.7.0 Firmware and this is the first time I've experienced this issue since getting the watch in May. I wasn't using any external sensors.

My watch has also been having an issue of rebooting while trying to save an activity. It started having the issue this past Sunday. Both times were runs over an hour and I'm running the latest software.

Same here. Restarting when trying to save activity during weekend trip to St. Moritz. After full reset saved next activity on 7th attempt.

Same issues on wife's 945 but eventually saved activity on +10th attempt without fulk reset. 

All fine once back home. 

Well, had the same issue after doing a long hike with navigation on, eventually activity got saved after the 10th try. Hope this bug gets fixed soon, it's really annoying as hell.

Same issue while skiing in high altitude (above 9000 ft in Chile). PulseOx was on. Had to click Save and wait for reboots more than 5 times. 

GARMIN please update the firmware. 

My watch is doing the same thing. I just went for a short run this morning at normalish altitude (Denver) and have tried to save 30 times to no avail!!! This happened yesterday with a hike as well, however, it saved after three attempts. On a side note, about 4-5 days ago my watch stopped tracking my sleep as well. Luckily I am still in my 30 day return policy with the store I bought it in and I am thinking about just going back to the apple watch (inferior tracking but at least it's reliable). Does anyone have any ideas on how to fix either issue?

Are you already at FW 2.8? In another thread there was a Garmin statement that 2.8 should contain a fix. I never had this issue therefore I can't say verify that.

Not fixed on 2.80, for hiking at least.