With code below I try to update the email address of a user. The $_POST is correct, but the data is not saved into wp_users table.
$user_id = $_POST['ID']; // correct ID wp_update_user( $user_id, 'user_email', $_POST['user_email']); // correct email address
Also tried this with success:
wp_update_user( array( $user_id, 'user_email', $_POST['user_email']) );
What is wrong with this update?