Apple Watch Series 9 will not pair with the phone

The checks in more detail

If the camera cannot read the animation, choose Pair Apple Watch Manually and enter the six-digit code. A Series 9 bought for a family member can be set up with Family Setup, which uses a different flow and needs an iPhone with iOS 17 or later; if the family member's iPhone setup fails, check the Family Setup requirements. For a new iPhone, Apple's page recommends backing up the old one and restoring the new one before pairing. Restart both devices, and try a different Wi-Fi network if setup stalls at the connecting step.

Set up can fail when the iPhone's Wi-Fi is on a captive portal network such as a hotel, because the watch needs to download software, so use a home network or a hotspot. Also check that your iPhone's date and time are set automatically, since a wrong clock stops the secure connection used during pairing. These simple checks fix many failures that look mysterious. If you have an older iPhone and the Series 9 is new, make sure the iPhone runs the minimum iOS required for the Series 9's watchOS, since the pairing will not complete if the iPhone is too old.

If your iPhone cannot update further, the watch cannot be set up with it. Check Apple's compatibility list for the watch before purchase if you plan to use an older iPhone. If the pairing keeps failing at the same step, try resetting the iPhone's network settings, which clears stored Wi-Fi and Bluetooth information that may be blocking the connection, and then start again. You will need to re-enter Wi-Fi passwords on the iPhone afterwards, but it often resolves a stubborn pairing problem without erasing data.