After trying several solutions proposed in this forum, the solution that finally worked for me is hard resetting your iPhone.
If you have an iPhone X or later (with no home button), follow these steps :
- click volume up button once
- click volume down button once
- click and maintain the lock button (on the right side) until the power goes off and the Apple logo appears.
This will refresh all the software on your phone.
After that, reset your Apple Watch, and start pairing it with your iPhone, you should see the software download bar, this may take a long time but right after it, you'll have the latest software updated and your Apple Watch up and running.
I solved this issue by uninstalling the Watch app from my iphone and reloading it. After reloading the app I paired the watch to the phone and the update started loading.
I will say one thing today was a frustrating day trying to get the watch to pair for a few hours. Finally I have success. My fix is the same as many but it took only one try when I changed the Country and Language. I decided to use language Portuguese, and country Afghanistan. It worked. so mad I could not see straight. But success, hope it works for you. It will.
Apple Watch 3, iPhone 11Pro w/ iOS 14.6 - nothing works to update the watch and make it a usable device, it's basically a dud now. I've tried resetting the iPhone and trying to update the watch in different language. No dice!