• Apple Support: Restart your Apple Watch
• Apple Support: Restart your iPhone, iPad, or iPod touch

The app crashes during measurement

The Apple Watch itself may be unstable, so please try restarting it.

We have seen many cases of crashes where the Zones app was not a factor.
If it's a problem with your Apple Watch or Apple Health, or a problem with watchOS, restarting your Apple Watch will often fix the problem.
Alternatively, it may be fixed by re-pairing the Apple Watch.

If you find a way to reproduce the crashes, it would be greatly appreciated if you could feedback us via Settings > Support > Feedback.

Recovery after a crash

If the Watch app crashes, the app will automatically recover and resume, or resume when the app is launched again.