! PCRE engine starting at rev 8.3, will not allow you to specify the surrogate range D800–DFFF

Sources/QueryString.php

@@ -551,7 +551,7 @@ function cleanXml($string)
 	global $context;
 
 	// http://www.w3.org/TR/2000/REC-xml-20001006#NT-Char
-	return preg_replace('~[\x00-\x08\x0B\x0C\x0E-\x19' . ($context['utf8'] ? '\x{D800}-\x{DFFF}\x{FFFE}\x{FFFF}' : '') . ']~' . ($context['utf8'] ? 'u' : ''), '', $string);
+	return preg_replace('~[\x00-\x08\x0B\x0C\x0E-\x19' . ($context['utf8'] ? '\x{FFFE}\x{FFFF}' : '') . ']~' . ($context['utf8'] ? 'u' : ''), '', $string);
 }
 
 /**