Apple Watch Series 9 update fails during pairing with iPhone 16 Pro Max

My apple watch series 9 i unpair to my old iphone14plus and i want to pair my new iphone 16promax but my apple watch need to be update i my new phone but i tried many times but it cannot update its always failed can you help me to fix my problem all i want is to pair to my new phone. I cannot pair unless i did not update the apple watch using my new phone

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