neotrope on "[Plugin: Yoast SEO] Sitemap XML Parsing Error"

Installed yoast 3.4 plugin on wordpress 4.5.3
Since the update Im now getting xml parse errors for the sitemaps

"XML Parsing Error: XML or text declaration not at start of entity"
looking at page source I can see there are two blank lines at the top of the page.
I know those lines cant be there, but how do I find where they are generated to get rid of them??

https://wordpress.org/plugins/wordpress-seo/

I am getting a similar sitemap error. Running WP 4.5.3 and Yoast SEO 3.4. I was experiencing this error on an older version and updated, first to 3.3.4, then to 3.4 today.

This page contains the following errors:

error on line 2 at column 6: XML declaration allowed only at the start of the document

Below is a rendering of the page up to the first error.

The above error is when viewing the page in Chrome. Line 1 is a blank line, which is the source of the problem.

This seems like a serious bug to me. It is technically incorrect XML even if some or most parsers do accept it. Is there some fix I can apply to remedy it, even if this bug report is not accepted by the maintainer?

My apologies. I see in another post that this is not from your plugin. Can you explain how the plugin is invoked so I can understand where the problem is occurring?

I often find after YOAST SEO upgrade (one presumes you are deleting old folder and adding new one, not "overwriting") ...

a) resave permalinks
b) clear transients with wp-optimize
c) go to Yoast > sitemaps "save"
d) change number from 1000 to 900; save
e) click link to sitemap on the yoast screen

Or, after above:
a) disable plugin on plugin menu
b) reactivate plugin

Should fix it unless you have conflict or other issue :-)