Had the same thing happened last week
It was around +20°C here in Toronto. I've been experiencing jerkiness at low gears while in traffic so I decided to switch gears in manual shift mode to see if the jerkiness would be better controlled, then Drivetrain Error showed up; manual shift mode automatically shifted to automatic and was stuck on 1st gear...luckily I was able to pull in at a parking lot and turned off the engine. Waited for a few minutes then re-started it...so far the error has not come back.
As for the jerking on lower gears/speed...I have gone back and forth (4 times) to the dealership and have it looked at. It would seem to be fixed but after a few weeks it would come back on/off unpredictably...now 4 years later and over 90k, my warranty is expired and the jerking problem was never fully fixed. I talked to the dealership and they are not being helpful...expired warranty, now I have to pay for any/every service. Any advice??? Thanks!