WordPress Development Stack Exchange is a question and answer site for WordPress developers and administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

On Firefox I get the following below the footer

`Performance Optimization WordPress Plugins by W3 EDGE

Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, 'Array' was given in /somedirectories/wordpress/wp-includes/plugin.php on line 405`

On Chrome it works fine and the last line on the footer is

Performance Optimization WordPress Plugins by W3 EDGE

share|improve this question
up vote 3 down vote accepted

This is not an error, it is a warning. You can make this go away by:

  • Fixing the warning
  • Write errors to the error log instead of the screen ( best practice )

To fix the error, I recommend looking at what's hooking into wp_footer etc, or using a PHP debugger

share|improve this answer
I have put /* All errors and warnings to file, instead of html screen */ define('WP_DEBUG_LOG', false); define('WP_DEBUG_DISPLAY', false); In the wp-config.php, but I still get warnings in the footer, when I use Firefox. – Siddharth Jun 28 '12 at 17:17
This is a PHP setting you need to make, the wordpress constants can't always be relied upon, they work on some server configurations but not others – Tom J Nowell Jun 29 '12 at 9:17

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.