Series 4 with iPhone 12 Pro Upgrading from watchOS 6.3 to 8.5.1 (from Series 1 watch) Series 4 is factory reset with no data USA Tried mostly everything listed here including Beem’s tutorial - nothing. What did end up working? Changed region to Canada on Watch (from Bring iPhone near Watch screen & click the i icon) & then begin pairing from Watch app. Update download immediately started with no error. Must be a conditional bug if iOS version or watchOS versions don’t match And region Does match, error message displays saying cannot connect update. Choosing alternate region bypasses condition, something like that. Also make sure, for safety, that both your Watch & iPhone are charging and/or charged beyond 50% before downloading begins. Hope this saves somebody hours or days of utter frustration.