Title: PHP error expects parameter 1 to be a valid callback
Last modified: August 31, 2016

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# PHP error expects parameter 1 to be a valid callback

 *  [enquirer32](https://wordpress.org/support/users/enquirer32/)
 * (@enquirer32)
 * [10 years, 4 months ago](https://wordpress.org/support/topic/php-error-expects-parameter-1-to-be-a-valid-callback/)
 * I have recently started obtaining this php message:
 * > PHP Warning: call_user_func_array() expects parameter 1 to be a valid callback,
   > function ‘_return_false’ not found or invalid function name in /myserver/public/
   > wp-includes/plugin.php on line 235
 * I see this has been noted before even going back a few years on different forums.
   There doesn’t seem to be a specific solution.
 * Does anyone know how I can troubleshoot this?

Viewing 5 replies - 1 through 5 (of 5 total)

 *  Moderator [James Huff](https://wordpress.org/support/users/macmanx/)
 * (@macmanx)
 * [10 years, 4 months ago](https://wordpress.org/support/topic/php-error-expects-parameter-1-to-be-a-valid-callback/#post-6923561)
 * Try [manually resetting your plugins](https://codex.wordpress.org/FAQ_Troubleshooting#How_to_deactivate_all_plugins_when_not_able_to_access_the_administrative_menus.3F)(
   no Dashboard access required). If that resolves the issue, reactivate each one
   individually until you find the cause.
 * If that does not resolve the issue, access your server via [SFTP or FTP](https://codex.wordpress.org/FTP_Clients),
   or a file manager in your hosting account’s control panel, navigate to `/wp-content/
   themes/` and rename the directory of your currently active theme. This will force
   the default theme to activate and hopefully rule-out a theme-specific issue (
   theme functions can interfere like plugins).
 *  Thread Starter [enquirer32](https://wordpress.org/support/users/enquirer32/)
 * (@enquirer32)
 * [10 years, 4 months ago](https://wordpress.org/support/topic/php-error-expects-parameter-1-to-be-a-valid-callback/#post-6923571)
 * Thanks. I think I found the issue – I had edited my theme functions file because
   I was getting this message:
 * > PHP Notice: The called constructor method for WP_Widget is deprecated since
   > version 4.3.0! Use __construct() instead. in /myserver/public/wp-includes/functions.
   > php on line 3624
 * with this:
 *     ```
       // to change warning for deprecated function
       add_filter('deprecated_constructor_trigger_error','_return_false');
       ```
   
 * Just swapped one error message with another. What to do?
 *  Moderator [James Huff](https://wordpress.org/support/users/macmanx/)
 * (@macmanx)
 * [10 years, 4 months ago](https://wordpress.org/support/topic/php-error-expects-parameter-1-to-be-a-valid-callback/#post-6923573)
 * See under “WP_Widget error” here for instructions on how to properly fix the 
   original issue: [https://wordpress.org/support/topic/read-this-first-wordpress-43-master-list?replies=4#post-7314897](https://wordpress.org/support/topic/read-this-first-wordpress-43-master-list?replies=4#post-7314897)
 *  Thread Starter [enquirer32](https://wordpress.org/support/users/enquirer32/)
 * (@enquirer32)
 * [10 years, 4 months ago](https://wordpress.org/support/topic/php-error-expects-parameter-1-to-be-a-valid-callback/#post-6923590)
 * Thanks but it’s not actually a solution to the problem. Anyway, I have ‘hidden’
   the error log…
 *  Moderator [James Huff](https://wordpress.org/support/users/macmanx/)
 * (@macmanx)
 * [10 years, 4 months ago](https://wordpress.org/support/topic/php-error-expects-parameter-1-to-be-a-valid-callback/#post-6923613)
 * Ah, sorry. There’s a second link there after the explanation which takes you 
   to the solution: [https://make.wordpress.org/core/2015/07/02/deprecating-php4-style-constructors-in-wordpress-4-3/](https://make.wordpress.org/core/2015/07/02/deprecating-php4-style-constructors-in-wordpress-4-3/)

Viewing 5 replies - 1 through 5 (of 5 total)

The topic ‘PHP error expects parameter 1 to be a valid callback’ is closed to new
replies.

## Tags

 * [parameter 1](https://wordpress.org/support/topic-tag/parameter-1/)
 * [PHP Warning](https://wordpress.org/support/topic-tag/php-warning/)

 * In: [Fixing WordPress](https://wordpress.org/support/forum/how-to-and-troubleshooting/)
 * 5 replies
 * 2 participants
 * Last reply from: [James Huff](https://wordpress.org/support/users/macmanx/)
 * Last activity: [10 years, 4 months ago](https://wordpress.org/support/topic/php-error-expects-parameter-1-to-be-a-valid-callback/#post-6923613)
 * Status: not resolved

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