I'm trying to update a site from 5.7.4.1 to 5.7.5.13 to 8.5.2 and running into problems.

The Heron theme on the live site does not work with 8.5.2. When I made a clean install of Concrete5, copied the Heron theme files from the live site to the new site, and activated Heron, it seemed to work, but when I tried to go to a page, I got this error message as shown in the attached jpg: Cannot access protected property Concrete\Core\Page\Page::$vObj and a pointer to line 30 of heron/elements/header_top.php that reads


When trying this same process with 5.7.5.13, I got the same error message, which I suspect is caused by the same issue. Looking at the 5.7.5 Release Notes, there seems to be significant changes from 5.7.4.

2 questions:
- What's the code that would resolve the error on this particular line?
- Is there detailed documentation for changes in 5.7.5 that I might run into in this theme?

Thanks,
Tim