Support » Fixing WordPress » 'PHP Warning: mb_stripos() empty delimiter' caused by wp-cron.php

  • Resolved J.D. Grimes


    I am getting the following errors in my PHP error_log:

    [16-Jan-2013 22:05:58 UTC] PHP Warning:  mb_stripos(): Empty delimiter in .../wp-includes/functions.php on line 658
    [16-Jan-2013 22:05:58 UTC] PHP Warning:  mb_stripos(): Empty delimiter in .../wp-includes/functions.php on line 661

    I compared the error log with the access logs, and found that these errors happen when the server POST‘s to wp-cron.php.

    What might be causing this? I did not get this error before upgrading to WP 3.5. I realize that this is only a warning, and I know how to silence it. I would just like to know what might actually be causing it. I think it might actually be causing wp-cron to fail, though no other errors are logged, because my site has not been automatically running the backWPup backups like it did before.

    Any advice would be greatly appreciated. 🙂

    P.S. I am using PHP 5.4, if that makes any difference.

    If you search Google with that error you will see that there are other people having the same problem.

Viewing 15 replies - 1 through 15 (of 18 total)
  • esmi


    Can you replicate the problem using the default theme with all plugins deactivated?

    Okay, activated 2012 theme, deactivated all plugins. Now do I just have to wait to see if I get the error, or can I run wp-cron somehow to test it? It only happens a few times a day.

    Okay, I am still getting the errors.



    Try re-uploading all files & folders – except the wp-content folder – from a fresh download of WordPress. Make sure that you delete the old copies of files & folder before uploading the new ones.

    I should point out that I’m not seeing any errors like this in my 12 or more WP 3.5 sites.

    Okay, I did that. I haven’t seen the error again yet, but like I said, it only happens a few times a day when the server runs wp-cron.php. I guess I have to just wait and see? Or could I try to test wp-cron somehow?

    Thanks for your help so far.



    You could try visiting the site using another browser to try and trigger wp-cron.php.

    I tried loging in via another browser, and then checked the access logs, and wp-cron didn’t run. So I guess now I just have to play the waiting game. I will keep checking the access logs.

    I did have a small issue when I upgraded to 3.5. The wp-includes folder wasn’t writable. But after I changed the permissions the install went fine. Maybe I missed something though. Hopefully this has fixed it. We will see. 🙂

    Unfortunately I am still getting this error. However, I figured out that the problem was not wp-cron. The error occurs whenever any of the /feed/ pages are visited. I guess it has something to do with RSS instead?

    I still have all plugins deactivated and the 2012 theme activated.

    I can create the error by visiting any of the /feed/ pages.



    Can we have a link to the site?


    It’s not pretty with everything disabled.

    The error occurs when a /feed/ page is visited that doesn’t have any posts to display. Visiting doesn’t seem to give the error, since it has posts to display. So I guess either something isn’t set up properly, or the values need to be checked with empty() before they are used in those places.

    Should I keep plugins deactivated, or do we know enough that I can activate them again?

    Thanks for walking me through this so far. I appreciate it. 🙂

    P.S. Above I said that the error occurs on the /feed/ page for a page that has no posts, I meant comments/posts. Actually, if you visit the feed for any page/post it logs the error, whether it has comments/posts to display or not.



    Um – what are you using to insert those code snippets into your Posts? They don’t seem to be in code tags and I’m not 100% sure that you’re encoding them before adding them to the Post content.

    A plugin. Which I still have disabled… 😉

    You said that you aren’t having this problem on any of your WordPress instals. Do you have PHP error reporting set to log PHP Warnings? And are you using PHP 5.4?



    Can you temporarily remove those Posts?

Viewing 15 replies - 1 through 15 (of 18 total)
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