Validation errors in 'dns-prefetch' codes

Site URL please?

HTML5 is fault tolerant, so minor markup errors like that don’t impact browser display or SEO.

You do need to fix missing closing divs and other errors that will impact layout. Read the validator report and carefully look at the html and php in your theme files. And make sure you have valid code in any post/pages you have edited in the WordPress editor.

That particular error you mention above can be fixed by unhooking DNS prefetch, but that can slow your site. Add

remove_action( 'wp_head', 'wp_resource_hints', 2 );

to your theme’s functions.php file.

But, you’re using Thesis, a premium theme not supported in these forums. So you need to get help from Thesis to edit their unique theme files.