r20212 introduced new methods for registering custom headers…

r20212 introduced new methods for registering custom headers and custom backgrounds. Everything now wraps add_theme_support(), and the various HEADER_ and BACKGROUND_ constants are gone.

This is ideally backwards compatible (I am cautiously optimistic), but because of the many factors at play here — child themeChild theme A Child Theme is a customized theme based upon a Parent Theme. It’s considered best practice to create a child theme if you want to modify the CSS of your theme. https://developer.wordpress.org/themes/advanced-topics/child-themes/. inheritance, constants, and theme support — it is very difficult to test.

I am going to come up with some sort of a testing protocol in the hope that we can crowd-source testing the WP.com themes that implement custom headers or backgrounds. For now at least, if you are running a theme with custom headerHeader The header of your site is typically the first thing people will experience. The masthead or header art located across the top of your page is part of the look and feel of your website. It can influence a visitor’s opinion about your content and you/ your organization’s brand. It may also look different on different screen sizes. or background support, please test and makemake A collection of P2 blogs at make.wordpress.org, which are the home to a number of contributor groups, including core development (make/core, formerly "wpdevel"), the UI working group (make/ui), translators (make/polyglots), the theme reviewers (make/themes), resources for plugin authors (make/plugins), and the accessibility working group (make/accessibility). sure functionality did not change.