Open Radar

 
Summary:
Third party workout apps hang on starting workout session is Apple Workout app has an active workout session. The call to HKWorkoutSession::startActivity will simply never return if another active workout session is running. 

Steps to Reproduce:
- Start a running workout using the Apple Workout app
- Start a third party workout app like Intervals Pro: Workout Timer or ProRun. For Intervals Pro, first create a running workout using the Walk/Run template
- Third party app hangs because its waiting for the workout session to either start or fail.
- Stop the Apple Workout app
- Kill the third party workout app
- The green sensor light remains until the watch is rebooted. 
- The third party app still doesn't work until the watch is restarted.

Expected Results:
- The third party app should get an error saying another workout session is active. This is what happened with previous version of watchOS.

Actual Results:
- The call to HKWorkoutSession::startActivity never returns

Version/Build:
watchOS 5 and 5.1

Configuration:
Series 4 watch, but likely all watches.