Title: “Warning: call_user_func_array()” when activating WPBruiser
Last modified: December 10, 2017

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# “Warning: call_user_func_array()” when activating WPBruiser

 *  Resolved [mariabernis](https://wordpress.org/support/users/mariabernis/)
 * (@mariabernis)
 * [8 years, 6 months ago](https://wordpress.org/support/topic/warning-call_user_func_array-when-activating-wpbruiser/)
 * I’m getting this error when activating WPBruiser plugin at the top of all my 
   site pages (latest 3.1.11 version):
 * `Warning: call_user_func_array() [function.call-user-func-array]: First argument
   is expected to be a valid callback, '__return_empty_string' was given in /somedir/
   dir/public_html/wp-includes/plugin.php on line 173`
 * `plugin.php line 173` is part of function `apply_filters($tag, $value)`.
    I’ve
   tried to narrow down which call to `apply_filters` inside one of WPBruiser’s 
   files is the one to blame, but can’t seem to find it.
 * I’m using wordpress 3.5.1. The plugin page claim is compatible starting at wp
   3.5.
 * Any help would be appreciated.

The topic ‘“Warning: call_user_func_array()” when activating WPBruiser’ is closed
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 * 0 replies
 * 1 participant
 * Last reply from: [mariabernis](https://wordpress.org/support/users/mariabernis/)
 * Last activity: [8 years, 6 months ago](https://wordpress.org/support/topic/warning-call_user_func_array-when-activating-wpbruiser/)
 * Status: resolved