why is my new email address not available to change my Apple ID?

why is my new email address not available to change my Apple ID?

Have you (or may be some one else) use that new email address as a rescue e-mail address?

Or ever deleted?

See -> Contact Apple for help with Apple ID account security

Contact Apple for help with Apple ID account security - Apple Support

Get more help:

Call Apple in your region see: Contact Apple for support and service

Contact Apple for support and service - Apple Support

or Contact Apple Support -> Get Support (apple.com)

FYI: You are sign in here .  .  .  with your Apple ID & Password (?).

Your Apple ID is the personal account you use with all Apple products and services. It includes the email address and password you use to sign in, as well as the contact, payment, and security details that you use with Apple.

You can’t merge multiple Apple ID accounts.