I know this has been mentioned before...
I took a new site live today and the w3c validator could not perform its duty and tossed a 500 server error at me.
The course I took to fix this was adding a missing semicolon in the Search Highlighting plugin (modx-0.9.6.3.)
The line
$highlight = strip_tags(urldecode($_REQUEST['highlight']))
is missing the semicolon at the end. Doing so fixed the 500 server error and I could resume validating my pages.
Just wondering if this issue was "on the radar..." ?
Max