Warning: Compilation failed error

Are you suffering from:

Warning: Compilation failed: characters with values > 255 are not yet supported in classes at offset 16 in /path/to/website/blog/wp-includes/shortcodes.php on line xxx.

Fix it by changing a line  in /wp-includes/shortcodes.php. Look for the section headed “function shortcode_parse_atts($text)” and change the preg_replace line with

$text = preg_replace("/[\x{00a0}\x{ff}]+/u", " ", $text);

This maintains the functionality but only includes the supported characters.

This error occurs when using a version of PHP with an outdated PCRE library.