Since 2 days, many users are hitting the issue where they are kicked out of the app, or having the Fitbit Excercise app crashing. The Fitbit help acknowledge the issue and propose the following:
To fix the issue where the Fitbit app unexpectedly crashes when you open the Exercise tile, follow these steps. Note you’ll need to log back into the Fitbit app with your email address and password.
- On your phone, open the Settings app.
- Tap Apps > Fitbit > Storage.
- Tap Clear Data.
- Open the Fitbit app and log in.
- Be sure to accept the requests for your phone to access your location, notifications, and other settings.
Thanks for taking the time to report this issue. I assure you that our team is aware and working on finding a resolution. I will be sure to keep you all updated as more information becomes available.
Quoted from Fitbit Help