Okay, the failure that gives the error

"Error Creating Page There was an internal error when updating the Page."

is a bug. Temporary fix is to exclude one of the required parameters in html_header.php.
Change <meta property="og:type" content="product"/> on line 27 to <!-- <meta property="og:type" content="product"/> -->

This is a bug reported and accepted on Oct 21. No telling when it gets fixed but I should get notified.