XML HTML 404 Error

Hey there,

I would 95% guarantee this will work for you. Although, I would like to here from Yoast to see if they could sometime rollout a fix on there end that folks could enable or disable as needed perhaps to fix this for everyone. It looks like a lot of people have it. It may have been a WP core update, some plugin, etc. All I know is it worked on over 10 WP sites I have (all different themes and plugins just now):

#1
https://piotrkrzyzek.com/wordpress-remove-blank-line-from-rss-feed-wordpress-error-on-line-2-at-column-6-xml-declaration-allowed-only-at-the-start-of-the-document/

Afterwards, go wp-admin/options-permalink.php and resave your permalinks.

Also, you may have to go to your Yoast XML sitemaps too and unchecked the XML sitemaps tick box>save>and then recheck it>save.

Let me know . . .

??