preg_match() Compilation failed: nothing to repeat at offset 1 in wp-includes/classes.php on line 210

[Denis-de-Bernardy]

and the same for line 211... it looks like we forgot to preg_quote something. related forum threads:

​http://www.google.com/search?hl=en&rls=en&q=+site:wordpress.org+wordpress+wp-includes/classes.php+on+line+210

var_dump($wp_rewrite->wp_rewrite_rules()) for a site that is affected:

array(64) {
  ["([0-9]+)/?$"]=>
  string(36) "index.php?now_reading_id=$matches[1]"
  ["tag/([^/]+)/?$"]=>
  string(37) "index.php?now_reading_tag=$matches[1]"
  ["search/?$"]=>
  string(33) "index.php?now_reading_search=true"
  ["reader/([^/]+)/?$"]=>
  string(62) "index.php?now_reading_library=1&now_reading_reader=$matches[1]"
  ["([^/]+)/([^/]+)/?$"]=>
  string(70) "index.php?now_reading_author=$matches[1]&now_reading_title=$matches[2]"
  ["([^/]+)/?$"]=>
  string(40) "index.php?now_reading_author=$matches[1]"
  ["?$"]=>
  string(31) "index.php?now_reading_library=1"
  ["robots\.txt$"]=>
  string(18) "index.php?robots=1"
  [".*wp-atom.php$"]=>
  string(19) "index.php?feed=atom"
  [".*wp-rdf.php$"]=>
  string(18) "index.php?feed=rdf"
  [".*wp-rss.php$"]=>
  string(18) "index.php?feed=rss"
  [".*wp-rss2.php$"]=>
  string(19) "index.php?feed=rss2"
  [".*wp-feed.php$"]=>
  string(19) "index.php?feed=feed"
  [".*wp-commentsrss2.php$"]=>
  string(34) "index.php?feed=rss2&withcomments=1"
  ["feed/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(27) "index.php?&feed=$matches[1]"
  ["(feed|rdf|rss|rss2|atom)/?$"]=>
  string(27) "index.php?&feed=$matches[1]"
  ["page/?([0-9]{1,})/?$"]=>
  string(28) "index.php?&paged=$matches[1]"
  ["comments/feed/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(42) "index.php?&feed=$matches[1]&withcomments=1"
  ["comments/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(42) "index.php?&feed=$matches[1]&withcomments=1"
  ["comments/page/?([0-9]{1,})/?$"]=>
  string(28) "index.php?&paged=$matches[1]"
  ["search/(.+)/feed/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(40) "index.php?s=$matches[1]&feed=$matches[2]"
  ["search/(.+)/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(40) "index.php?s=$matches[1]&feed=$matches[2]"
  ["search/(.+)/page/?([0-9]{1,})/?$"]=>
  string(41) "index.php?s=$matches[1]&paged=$matches[2]"
  ["search/(.+)/?$"]=>
  string(23) "index.php?s=$matches[1]"
  ["category/(.+?)/feed/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(52) "index.php?category_name=$matches[1]&feed=$matches[2]"
  ["category/(.+?)/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(52) "index.php?category_name=$matches[1]&feed=$matches[2]"
  ["category/(.+?)/page/?([0-9]{1,})/?$"]=>
  string(53) "index.php?category_name=$matches[1]&paged=$matches[2]"
  ["category/(.+?)/?$"]=>
  string(35) "index.php?category_name=$matches[1]"
  ["tags/(.+?)/feed/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(42) "index.php?tag=$matches[1]&feed=$matches[2]"
  ["tags/(.+?)/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(42) "index.php?tag=$matches[1]&feed=$matches[2]"
  ["tags/(.+?)/page/?([0-9]{1,})/?$"]=>
  string(43) "index.php?tag=$matches[1]&paged=$matches[2]"
  ["tags/(.+?)/?$"]=>
  string(25) "index.php?tag=$matches[1]"
  ["author/([^/]+)/feed/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(50) "index.php?author_name=$matches[1]&feed=$matches[2]"
  ["author/([^/]+)/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(50) "index.php?author_name=$matches[1]&feed=$matches[2]"
  ["author/([^/]+)/page/?([0-9]{1,})/?$"]=>
  string(51) "index.php?author_name=$matches[1]&paged=$matches[2]"
  ["author/([^/]+)/?$"]=>
  string(33) "index.php?author_name=$matches[1]"
  ["([0-9]{4})/([0-9]{1,2})/([0-9]{1,2})/feed/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(80) "index.php?year=$matches[1]&monthnum=$matches[2]&day=$matches[3]&feed=$matches[4]"
  ["([0-9]{4})/([0-9]{1,2})/([0-9]{1,2})/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(80) "index.php?year=$matches[1]&monthnum=$matches[2]&day=$matches[3]&feed=$matches[4]"
  ["([0-9]{4})/([0-9]{1,2})/([0-9]{1,2})/page/?([0-9]{1,})/?$"]=>
  string(81) "index.php?year=$matches[1]&monthnum=$matches[2]&day=$matches[3]&paged=$matches[4]"
  ["([0-9]{4})/([0-9]{1,2})/([0-9]{1,2})/?$"]=>
  string(63) "index.php?year=$matches[1]&monthnum=$matches[2]&day=$matches[3]"
  ["([0-9]{4})/([0-9]{1,2})/feed/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(64) "index.php?year=$matches[1]&monthnum=$matches[2]&feed=$matches[3]"
  ["([0-9]{4})/([0-9]{1,2})/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(64) "index.php?year=$matches[1]&monthnum=$matches[2]&feed=$matches[3]"
  ["([0-9]{4})/([0-9]{1,2})/page/?([0-9]{1,})/?$"]=>
  string(65) "index.php?year=$matches[1]&monthnum=$matches[2]&paged=$matches[3]"
  ["([0-9]{4})/([0-9]{1,2})/?$"]=>
  string(47) "index.php?year=$matches[1]&monthnum=$matches[2]"
  ["([0-9]{4})/feed/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(43) "index.php?year=$matches[1]&feed=$matches[2]"
  ["([0-9]{4})/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(43) "index.php?year=$matches[1]&feed=$matches[2]"
  ["([0-9]{4})/page/?([0-9]{1,})/?$"]=>
  string(44) "index.php?year=$matches[1]&paged=$matches[2]"
  ["([0-9]{4})/?$"]=>
  string(26) "index.php?year=$matches[1]"
  ["[^/]+/attachment/([^/]+)/?$"]=>
  string(32) "index.php?attachment=$matches[1]"
  ["[^/]+/attachment/([^/]+)/trackback/?$"]=>
  string(37) "index.php?attachment=$matches[1]&tb=1"
  ["[^/]+/attachment/([^/]+)/feed/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(49) "index.php?attachment=$matches[1]&feed=$matches[2]"
  ["[^/]+/attachment/([^/]+)/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(49) "index.php?attachment=$matches[1]&feed=$matches[2]"
  ["[^/]+/attachment/([^/]+)/comment-page-([0-9]{1,})/?$"]=>
  string(50) "index.php?attachment=$matches[1]&cpage=$matches[2]"
  ["([^/]+)/trackback/?$"]=>
  string(31) "index.php?name=$matches[1]&tb=1"
  ["([^/]+)/feed/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(43) "index.php?name=$matches[1]&feed=$matches[2]"
  ["([^/]+)/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(43) "index.php?name=$matches[1]&feed=$matches[2]"
  ["([^/]+)/page/?([0-9]{1,})/?$"]=>
  string(44) "index.php?name=$matches[1]&paged=$matches[2]"
  ["([^/]+)/comment-page-([0-9]{1,})/?$"]=>
  string(44) "index.php?name=$matches[1]&cpage=$matches[2]"
  ["([^/]+)(/[0-9]+)?/?$"]=>
  string(43) "index.php?name=$matches[1]&page=$matches[2]"
  ["[^/]+/([^/]+)/?$"]=>
  string(32) "index.php?attachment=$matches[1]"
  ["[^/]+/([^/]+)/trackback/?$"]=>
  string(37) "index.php?attachment=$matches[1]&tb=1"
  ["[^/]+/([^/]+)/feed/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(49) "index.php?attachment=$matches[1]&feed=$matches[2]"
  ["[^/]+/([^/]+)/(feed|rdf|rss|rss2|atom)/?$"]=>
  string(49) "index.php?attachment=$matches[1]&feed=$matches[2]"
  ["[^/]+/([^/]+)/comment-page-([0-9]{1,})/?$"]=>
  string(50) "index.php?attachment=$matches[1]&cpage=$matches[2]"
}

The ?$ from now reading is causing this...

Yea, I just traced it down to that as well.