Title: error on wp-includes/plugin.php
Last modified: August 30, 2016

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# error on wp-includes/plugin.php

 *  [rytisg](https://wordpress.org/support/users/rytisg/)
 * (@rytisg)
 * [10 years, 5 months ago](https://wordpress.org/support/topic/error-on-wp-includespluginphp/)
 * Hey. Yesterday I was editing Woocommerce plugin when my site went blank. Specifically**
   mysite->wp-content->plugins->woocommerce->includes->class-wc-countries.php** 
   I deleted the edits I made via FTP and the site went live again, but now there’s
   an error **“Warning: call_user_func_array() [function.call-user-func-array]: 
   First argument is expected to be a valid callback, ‘WC_visibility_Tab::activate_filter’
   was given in /srv/disk10/2014103/www/mysite.com/wp-includes/plugin.php on line
   525”**
 * Line 525 is `call_user_func_array($the_['function'], array_slice($args, 0, (int)
   $the_['accepted_args']));`
 * How do I fix this?
 * EDIT: After yesterday’s messing about, I’m also getting this infinite spinner
   on checkout.

Viewing 1 replies (of 1 total)

 *  Thread Starter [rytisg](https://wordpress.org/support/users/rytisg/)
 * (@rytisg)
 * [10 years, 5 months ago](https://wordpress.org/support/topic/error-on-wp-includespluginphp/#post-6868688)
 * Moreover, whenever I try to activate or deactivate any plugin, I get an error:
 *  **Warning: Cannot modify header information – headers already sent by (output
   started at /srv/disk10/2014103/www/mysite.com/wp-includes/plugin.php:525) in /
   srv/disk10/2014103/www/mysite.com/wp-includes/pluggable.php on line 1228**

Viewing 1 replies (of 1 total)

The topic ‘error on wp-includes/plugin.php’ is closed to new replies.

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 * [WooCommerce](https://wordpress.org/plugins/woocommerce/)
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 * 1 reply
 * 1 participant
 * Last reply from: [rytisg](https://wordpress.org/support/users/rytisg/)
 * Last activity: [10 years, 5 months ago](https://wordpress.org/support/topic/error-on-wp-includespluginphp/#post-6868688)
 * Status: not resolved