Oh sorry overread that
Used
Remove Google form your Setup > Options > XML Sitemap Generation > Automatically submit sitemap to search engines list.
and removed the old invalid Google URL (Bing still offers this feature).
It's on the Xenforo site. They have to update the code and remove the feature that is pinging the sitemap to google to a none existent url (return http 500 error). Google stopped support of the feature because mostly spam was submitted...