thewisebaby

Fixed by checking exclude post type:

Tags (post_tag)

I am getting the same errors in Google Webmaster tools. Using a custom Hybrid theme and latest version of Yoast SEO. I tried using a different sitemap plugin and traffic declined significantly. The error reads as follows:

“An invalid date was found. Please fix the date or formatting before resubmitting.”
Parent tag: sitemap
Tag: lastmod
Line: 17

Parent tag: sitemap
Tag: lastmod
Line: 21

Same question here. Has anyone come up with a solution?