I'm testing Stack Overflow website using Google schema tester tool and it throws an error for the title:
Any idea why Google cannot determine that title as a QAwebpage? What's wrong with it?
They're using both
title to declare the page's title.
<meta name="twitter:title" property="og:title" itemprop="title name" content="Why google cannot detect QApages for a title?" />
The latter (
title) isn't part of
QAPage (see https://schema.org/QAPage), hence the error.
Screenshot shows full validation after editing per the above.