Random HTTP 500 error in WordPress

Question

I'm running WordPress 3.2.1 on a CentOS box and I'm getting reports from my writers saying they get HTTP 500 errors when they try to update an exciting post.

I've tried the same and have similar problems (although the HTTP 500 only shows in Chrome, Safari and Firefox simply give me a blank window).

I've increased my log level on my httpd install to debug but I still can't find any errors in the logs....

The same box is running another website as well, also using WordPress (same version) and this site is not displaying these symptoms.

All suggestions on how to resolve this are more than welcome!

EDIT: I should also add that I've already tried increasing the PHP Memory in wp-config.php (up the 64MB) but the problem still occurs)

(I'm double-posting this between here and serverfault as I'm not sure wether the problem is related to the server itself or to wordpress...)

Answer 1

If the problem is easily reproducible (i.e. you can make it happen again and again by following a set of steps), do this:

• Step 1: Document the steps required to cause the problem.
• Step 2: Document all of the plugins you have running
• Step 3: Deactivate all of your plugins!
• Step 4: Perform the steps outlined in step 1
• Step 5: If it's still broken, then you've got a config error somewhere on your server.
• Step 6: Activate the first plugin in the list from step 2.
• Step 7: Perform the steps outlined in step 1
• Step 8: Repeat steps 6-7 with every plugin until the site breaks to figure out what the culprit is.

I had this recently happen on my system, and it turned out to be a name conflict between two plugins I had running on my site.

Also, enable WP_DEBUG in your wp-config.php file ... you might see a better error message, but no promises.