I am 4 years late to this thread but after a couple of years trying to connect my Apple Watch Series 3 to my iPhone 12 Pro Max with no luck I have finally figured out a solution for myself. I’ll share it in hopes of helping someone else. I completely gave up trying to connect it to my new iPhone. (12 pro max) It just wasn’t going to work no matter what I tried. So I got out my old iPhone (iPhone SE) from my closet. Note: 1: There is NO SIM card in the old iPhone (SE) 2: I used my new iPhone (12) hotspot as Wi-Fi. 3: On the iPhone (SE) I deleted the watch app 4: I force restart the iPhone (SE) (Press and quickly release the volume up button. Press and quickly release the volume down button. Press and hold the side button. When the Apple logo appears, release the side button.) - Works for majority of older phones. 5: I factory reset the Apple Watch to pairing mode. 6: I re downloaded the watch app. 7: I reset the network settings on iPhone. (Settings-General-Reset or it may say Transfer or Reset IPhone) Clicked on Reset then click Reset Network Settings in pop up Reset Menu. 8: Both Apple Watch & iPhone SE were connected to chargers. (The whole time) 9: Once everything was loaded back up & connected back to Wi-Fi. (Must Re enter Wi-Fi password so don’t forget it.) I opened the watch app on iPhone (SE) then set phone down. 10: Picked up Apple Watch. Chose location. ( A location I was not in) (Canada) then hit continue until the picture that your phone scans popped up. Used the iPhone SE camera to connect. Brought me back to the watch app. Then it said that awful message that the Apple Watch needed to be updated to finish pairing. I clicked yes to update so of course it took me to the checking for update screen. This time though In about 8 seconds a message popped up saying that I would need to update my iPhone in order to update my Apple Watch so I clicked yes (to phone update). I was surprised because I’ve never gotten that far before. I then waited for the phone to update. (The long dreadful Requesting Update download) While I was waiting on that I decided to check back at what the watch app looked like. LO AND BEHOLD it was actually loading. I had to wait for my iPhone to finish updating of course but it finally did. Once the phone came back on I went straight to watch app. Refreshed back into the loading update for Apple Watch. Took 30 mins in all to download the update. (Not Including all the steps I took before this) Haven't tried pairing it to my new phone just yet because all I really wanted was for this Watch to just have the “required update” it needed. I’ll update when I decide to do that. If I can do that. Anyway, If you have an older iPhone, one you don’t care about resetting the network settings and don’t have a SIM card in or plan on putting one in then maybe this is worth a shot for you to try. I truly hope this works for someone. Specially since a lot of everyone’s problems seem to be the same but not everyone solutions work.