I had this problem after updating from v9.1 to v9.6.1, but we also experienced it after editing a page in 9.1 before updating — we’d edited the About page probably ~100 times, and after a routine edit, the page became broken and would no longer load in TD Composer. TagDiv really needs to include better error messaging for this sort of thing. Why are you showing an error message if no one, including your developers, can say for certain what it means or where the problem is?

The problem we had after updating came from our custom child theme code — We updated our child header.php based on the newest header.php in Newspaper but still had the super helpful “Error at zones: 5 (models) : 1 (dom)” message when opening a brand new Page in TD Composer. Turns out the existence of <div class="tdc-content-wrap"> in our custom footer template was enough to break Composer. Oops. Changing that to <div class="td-container td-footer-bottom-full"> fixed the problem and we could edit Pages again.

The About page problem was even more fun to track down. Long story short, my manager had edited a raw HTML section and not closed off a <div> with a matching </div> and saved the page. TD Composer then started throwing the “Error at zones” error and the page was no longer editable. The fix? Take the offending raw HTML string from the text editor, base64_decode() it, rawurldecode() it, fix the markup, rawurlencode() it, base64_encode() it, paste it back in the text editor, and save. Now the page is editable again. Seems like maybe not the greatest system.