Title: call_user_func_array() expects parameter 1 to be a valid callback
Last modified: September 1, 2016

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# call_user_func_array() expects parameter 1 to be a valid callback

 *  Resolved [Kreeger](https://wordpress.org/support/users/kreeger/)
 * (@kreeger)
 * [10 years ago](https://wordpress.org/support/topic/call_user_func_array-expects-parameter-1-to-be-a-valid-callback-9/)
 * Hello,
 * It seems there is a little problem with the last update: I get 20 messages like
   this one when I save the plugin settings:
 * `Warning: call_user_func_array() expects parameter 1 to be a valid callback, 
   function 'boolval' not found or invalid function name in /var/www/vhosts/max/
   httpdocs/wordpress_test/dev/wp-includes/plugin.php on line 235`
 * And finally at the end:
 * `Warning: Cannot modify header information - headers already sent by (output 
   started at /var/www/vhosts/max/httpdocs/wordpress_test/dev/wp-includes/plugin.
   php:235) in /var/www/vhosts/max/httpdocs/wordpress_test/dev/wp-includes/pluggable.
   php on line 1171`
 * NB: I use only Ewww Image Optimize on my current dev website
 * [https://wordpress.org/plugins/ewww-image-optimizer/](https://wordpress.org/plugins/ewww-image-optimizer/)

Viewing 3 replies - 1 through 3 (of 3 total)

 *  Plugin Author [Shane Bishop](https://wordpress.org/support/users/nosilver4u/)
 * (@nosilver4u)
 * [10 years ago](https://wordpress.org/support/topic/call_user_func_array-expects-parameter-1-to-be-a-valid-callback-9/#post-7461278)
 * Thanks, I didn’t realize boolval() was that new. I’ll add in a dummy function
   and get a fix out.
 * Alternatively, you can upgrade to PHP 5.5 and that will fix it.
 *  Plugin Author [Shane Bishop](https://wordpress.org/support/users/nosilver4u/)
 * (@nosilver4u)
 * [10 years ago](https://wordpress.org/support/topic/call_user_func_array-expects-parameter-1-to-be-a-valid-callback-9/#post-7461281)
 * wait a few minutes, and 2.8.5 will be out with the fix
 *  Thread Starter [Kreeger](https://wordpress.org/support/users/kreeger/)
 * (@kreeger)
 * [10 years ago](https://wordpress.org/support/topic/call_user_func_array-expects-parameter-1-to-be-a-valid-callback-9/#post-7461286)
 * I can not upgrade to a newer PHP version at this time.
 * PS: You rock!

Viewing 3 replies - 1 through 3 (of 3 total)

The topic ‘call_user_func_array() expects parameter 1 to be a valid callback’ is
closed to new replies.

 * ![](https://ps.w.org/ewww-image-optimizer/assets/icon-256x256.png?rev=1582276)
 * [EWWW Image Optimizer](https://wordpress.org/plugins/ewww-image-optimizer/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/ewww-image-optimizer/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/ewww-image-optimizer/)
 * [Active Topics](https://wordpress.org/support/plugin/ewww-image-optimizer/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/ewww-image-optimizer/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/ewww-image-optimizer/reviews/)

 * 3 replies
 * 2 participants
 * Last reply from: [Kreeger](https://wordpress.org/support/users/kreeger/)
 * Last activity: [10 years ago](https://wordpress.org/support/topic/call_user_func_array-expects-parameter-1-to-be-a-valid-callback-9/#post-7461286)
 * Status: resolved