Support » Plugin: WordPress HTTPS (SSL) » Warning: preg_match(): Unknown modifier 'c' in /DomainMapping.php on line 43

  • Resolved Marco Florian


    I receive this warning message three times when I’m in the /checkout page:

    Warning: preg_match(): Unknown modifier 'c' in /home/grievingtogether/public_html/wp-content/plugins/wordpress-https/lib/WordPressHTTPS/Module/DomainMapping.php on line 43


    SSL Host:
    Port: blank
    Force SSL Admin: checked
    Force SSL Exclusively: checked
    Remove Unsecure Elements: unchecked
    Debug Mode: unchecked
    Proxy: No
    Admin Menu Location: Settings.

    Secure Filters:

    I’m using WordPress 3.8.1. Also, the HTTPS is working just fine, but with those warnings at the top of the page.


Viewing 7 replies - 1 through 7 (of 7 total)
  • I went to the line and tried a few things.

    (1) preg_quote($http_domain, ‘/’)
    – This would change “\” to “\\d\.gravatar\.com”. Which is right, but we need the \d to be parsed as regexp.

    (2) preg_match(‘|’ . $http_domain . ‘|’, $url, $matches);
    – I changed the delimiters to another character, but again, we could be using it inside the regexp.

    (3) str_replace(‘/’, ‘\/’, $http_domain)
    – I just decided to use this one. It is working fine, no more warnings. Try it out and make the fix if applicable and/or give me a recommendation please.



    I’m having the same problem.

    The “preg_match(): Unknown modifier ‘c’ in /home/grievingtogether/public_html/wp-content/plugins/wordpress-https/lib/WordPressHTTPS/Module/DomainMapping.php on line 43”

    isn’t on all the pages. Main homepage, main tabs are working fine. Except when I go to the menu and scroll down and select.

    I’m not sure what’s going on.

    The website is

    You can see the error on

    Any help would be greatly appreciated.


    Go to the file and line below:

    /wp-content/plugins/wordpress-https/lib/WordPressHTTPS/Module/DomainMapping.php on line 43


    preg_match(‘/’ . $http_domain . ‘/’, $url, $matches);


    preg_match(‘/’ . str_replace(‘/’, ‘\/’, $http_domain) . ‘/’, $url, $matches);

    Hi Marco,

    thanks so much!

    It works.

    Glad to help. You’re welcome 🙂

    Marking it as solve.

    Well, actually, the plugin author should apply this fix. Hope he/she does. Still a great plugin! Thanks.



    Perhaps they should but I guess they didn’t ’cause I ran into the same problem (WordPress 4.0, plugin WordPress HTTPS 3.3.6) but with a ‘p’ instead of ‘c’. But it seems like the same solution as you proposed above did the trick, again 🙂
    Great stuff, thanks !

    No more Warnings 🙂

Viewing 7 replies - 1 through 7 (of 7 total)
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