Active or Disabled action button in a mobile form?

I have a "change password" screen where the user's password has expired and he/she has to change it. it's a standard screen with "New password" and "Re-type new password" fields, with an inline validation that checks whether the password guidelines are met (while the user is typing): 8 characters, 1 digit, 1 number, 1 special character.

we have an argument whether the main "change password" action button should be disabled until all the validations are clear, or to keep it active and provide an error message if needed.

what do you think is better?