Thank you for reaching out to the API Support team here at Constant Contact.
I received the following error when doing a PUT making no changes to the contact:
400 Bad Request
"error_message": "#/addresses/0/state_code: This attribute value is not a valid US State or Canadian Province."
This appears to be an issue with our API not accepting "PR" as a valid state code. I will look into this as a possible bug. In the meantime, if you remove the state_code field from your PUT, you can keep the state field as "Puerto Rico" and your changes will be accepted.
API Support Specialist
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