--TEST-- MessageFormatter::format() invalid UTF-8 for arg key or value --SKIPIF-- format(array("foo" => 7, "\x80" => "bar"))); var_dump($mf->format(array("foo" => "\x80"))); --EXPECTF-- Warning: MessageFormatter::format(): Invalid UTF-8 data in argument key: '€' in %s on line %d bool(false) Warning: MessageFormatter::format(): Invalid UTF-8 data in string argument: '€' in %s on line %d bool(false)