Error: call_user_func_array() expects parameter 1 to be a valid callback

I have issue after upgrading my wordpress to 3.6 see below for errors which displays on wordpress admin panel not on front of website.

Warning: call_user_func_array() expects parameter 1 to be a valid callback, function ‘regis_options’ not found or invalid function name in wp-includes/plugin.php on line 406

Warning: Cannot modify header information – headers already sent by (output started at wp-includes/plugin.php:406) in wp-includes/option.php on line 571

Warning: Cannot modify header information – headers already sent by (output started at wp-includes/plugin.php:406) in wp-includes/option.php on line 572

Answers:

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Method 1

Somewhere in your theme or plugins is a line like this:

add_filter( 'something', 'regis_options' );

Could also be add_action(). Find that piece of code and remove or fix it.

The other errors are a result of the first one. The printed error message causes output and hence HTTP headers, so PHP/WP cannot send other headers anymore. They will go away when you fix the first error.

Method 2

Warning: call_user_func_array()

It is usually caused by a filter or an action not properly declared.

add_filter ( 'action_tag' , array( $this , 'my_callback' ) , 30 );

The priority must be outside the callback array parameter. this fixed my issue.

Method 3

Hi try this solution :

Add this in functions.php:

function regis_options($args) {
   return $args;
}

Also add this in your class-wp-hook.php:

public function regis_options($args) {
echo '<pre>' . var_export($args, true) . '</pre>';
echo '<pre>' . var_dump(debug_backtrace()) . '</pre>';
return $args;
}

Method 4

I had put a space at the end on my call back string on calling the filter

add_filter( 'something', 'regis_options ' );

Instead of

add_filter( 'something', 'regis_options');

Method 5

This error will also happen when you call for a function that does not exist.
to solve it
you need to define the ‘regis_options’ function
try something like

function regis_options(){ 
echo 'test';
}

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0