SiteMap Error

Our sitemap is throwing an error:

This page contains the following errors:
error on line 1 at column 6: Extra content at the end of the document
Below is a rendering of the page up to the first error.

This problem is on the recent version. The old version does not have this problem. For now, we’ve disabled this feature and run a separate sitemap plugin to compensate.

https://wordpress.org/plugins/all-in-one-seo-pack/