@mhbeyle, I’m not getting the error you report, using HTML5 doctype.
@ifaist0s and @vaakash:
Wrapping in rawurlencode seems to fix the whitespace errors.
I made the following changes, and my pages now validate. If you try this, please back up the file first.
In wpsr-socialbuttons.php:
Change Line 160 to
‘$deTitle = rawurlencode(trim($pTitle));’
Change Line 163 to
‘$deExcerpt = rawurlencode(htmlspecialchars($pExcerpt));’
Hope this helps someone.