I understand that when trying to make a purchase on your iPhone, you get an error that you have an invalid address. I'm happy to provide some help for this issue.
Use the steps in the following article to check your payment information and ensure that your address is correct:
Change or remove your Apple ID payment information - Apple Support
On your iPhone, iPad, or iPod touch
- Go to Settings > [your name] > Payment & Shipping.
- Tap Payment Method, then edit your payment details. If you want to remove your payment method or change to a different payment method, scroll to the bottom of the Payment Details screen and tap Change Payment Method. Then select None or a different payment method.
Learn what to do if you don't see None or can't select it and if additional payment methods are available in your country or region.
- Make sure your name and billing address exactly match the information on file with your financial institution. Then tap Save.
If you change your payment method to a credit card, the iTunes Store places a temporary authorization hold on your credit card to verify your updated account information. You might also see an option to add the new card to Apple Pay.
Let us know how that works out for you, and thanks for using the Apple Support Communities. Cheers!