I managed to solve this issue as well now. I tried all the weird solutions listed in this thread but none of them worked. What did actually solve it in the end was to just charge the watch before attempting to do the update. I'm pretty sure the actual solution for all previous posts in this thread isn't the actual resets etc they've done, but just that they've had the watch in the charger during the procedure so the battery has eventually reached its 50% and therefore been able to start the update.
The real bug here is the UX of the Watch app on the phone that doesn't tell you this but instead lets you think it's due to a network failure.
@apple please update the UX in the watch app so we get a proper message about this, it would have saved myself and tons of other people around the world a lot of frustration.
And again, for everyone struggling with this, just leave the watch on the charger for 1-2 hours to get it fully charged, and attempt the update again and it should work.
Topic:
App & System Services
SubTopic:
Core OS
Tags: