So my wordpress site keeps going down from a 500 error, about once a day now.

The entire site, including the wp-admin, will go down and stop responding to all requests with a 500 error.

If I enable WP_Debug I only get a warning: Warning: Illegal offset type in ...../wp-includes/cron.php on line 99

The warning is the ONLY thing that appears on the site when WP_Debug is enabled, nothing else. All requests are blank except for that warning.

When I check my server logs I can see that just before the 500 error started happening a PHP script ran out of memory: PHP Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 560537 bytes) in .../wp-includes/functions.php on line 434

All out of memory errors happen on the same PHP file at the same line. I know what you're going to say, "Bump up the memory in your php.ini". Well, it's already 128MB so I'm not sure that's the right answer. This configuration ran fine for months, this just started happening a few days ago.

Restarting Apache2 temporarily resolve the problem, until the next day.

The server this is happening on is shared with several dozen other wordpress sites, they are all unaffected by the problem this site is experiencing.

I'm tearing my hair out over here. There's a 500 server error happening and there's ZERO logging/reporting to tell me what's causing it, then it magically disappears for 24 hours if I restart Apache.


Thanks for the response! I guess I didn't want to go through the process of disabling 30 plugins and retrying them one at a time.

Sometimes I forget that this stuff isn't magic.

Anyway, I did exactly that and found the culprit plugin to be Cornerstone. A thread on the X Theme support forum made a suggestion to bump the memory limit up to 256MB. Once I did that Cornerstone stopped causing the site to 500 error (So far). Kind of insane to me that a Wordpress plugin could need a quarter of a gigabyte of RAM but whatever, it's working now. Thanks!

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  • I do not know what this plugin does, but I'm almost very sure that it is doing something very wrong for WordPress to run out of memory. Instead of bumping memory up, I would suggest at looking why the plugin needs so much memory. IMHO, I would just try and look for a replacement with better performance, or code my own plugin ;-) – Pieter Goosen Mar 15 '16 at 8:15

Your question is really hard to answer without knowing more information, like which theme and plugins you are using.

For starters, I suggest that you try to disable your plugins one-by-one, and see if the issue goes away. This way, we will be able to figure out what specific part of your Wordpress is causing the issue.

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