Am seeing this error on a fresh install of Spark. This only happens on the default Home page (if you go to the default About Us page the Change Layout and Customize Page options are not there). If you select any of the three layout options at the top of the page (320px, 760px or 1010px) and then click on the Change Layout or Customize Page options at the bottom of the page, you get the following error:
An AJAX HTTP request terminated abnormally.
Debugging information follows.
In Chrome the error stays open until you click OK and then directs to a page with code. In Firefox the error blinks open for a moment and then automatically redirects you to the same page with code.