After my watch updated to iSO 26.2 the activity rings stopped working and the fitness app won’t work. I have followed all the trouble shooting steps and still nothing. The only thing that does work is deleting the watch and reinstalling but that will only last for a day or two.
Apple Watch SE, watchOS 26
To rule out a software issue inside your backup data, erase the watch and pair it again, setting it up as a new device. You will only lose your created Watch faces and may have to activate the cards in your Wallet app again.
Then test, if the Fitness app works as expected.
Unpair and erase your Apple Watch - Apple Support
To rule out a software issue inside your backup data, erase the watch and pair it again, setting it up as a new device. You will only lose your created Watch faces and may have to activate the cards in your Wallet app again.
Then test, if the Fitness app works as expected.
Unpair and erase your Apple Watch - Apple Support
Apple Watch activity rings and fitness app not working
