Title: plugin does not work
Last modified: February 28, 2022

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# plugin does not work

 *  Resolved [nicado](https://wordpress.org/support/users/nicado/)
 * (@nicado)
 * [4 years, 2 months ago](https://wordpress.org/support/topic/plugin-does-not-work-204/)
 * only woocommerce and woo instant plugins installed
 * wordpress 5.9.1
 *     ```
       Warning: Undefined array key 0 in /home/*********/public_html/wp-includes/plugin.php on line 957
   
       Warning: Undefined array key 0 in /home/*********/public_html/wp-includes/plugin.php on line 960
   
       Warning: Cannot modify header information - headers already sent by (output started at /home/*********/public_html/wp-includes/plugin.php:957) in /home/*********/public_html/wp-includes/functions.php on line 6821
   
       Warning: Cannot modify header information - headers already sent by (output started at /home/*********/public_html/wp-includes/plugin.php:957) in /home/*********/public_html/wp-admin/includes/misc.php on line 1310
   
       Warning: Cannot modify header information - headers already sent by (output started at /home/*********/public_html/wp-includes/plugin.php:957) in /home/*********/public_html/wp-admin/admin-header.php on line 9
       ```
   

Viewing 9 replies - 1 through 9 (of 9 total)

 *  Plugin Author [Georgi Bakalski](https://wordpress.org/support/users/irdroid/)
 * (@irdroid)
 * [4 years, 2 months ago](https://wordpress.org/support/topic/plugin-does-not-work-204/#post-15411920)
 * Probably your theme is modifying the headers and thus incompatible with the plugin,
   you can change the theme or disable the function in your theme that is rendering
   incompatibility. If you are sure that there are no other plugins that is the 
   most probable cause. Some themes are messing with the wordpress emails and thus
   making these issues.
    -  This reply was modified 4 years, 2 months ago by [Georgi Bakalski](https://wordpress.org/support/users/irdroid/).
 *  Thread Starter [nicado](https://wordpress.org/support/users/nicado/)
 * (@nicado)
 * [4 years, 2 months ago](https://wordpress.org/support/topic/plugin-does-not-work-204/#post-15413710)
 * I changed the theme to the wordpress defaults and nothing changed.
    I disabled
   woocommerce emails and nothing has changed, I don’t think so and the themes
 *  Plugin Author [Georgi Bakalski](https://wordpress.org/support/users/irdroid/)
 * (@irdroid)
 * [4 years, 2 months ago](https://wordpress.org/support/topic/plugin-does-not-work-204/#post-15413993)
 * Are you self hosting the site or is it on a commercial hosting server? We have
   a testing environment with 5.9.1 and the plugin is working flawlessly. So maybe
   you have some other problem?
 *  Thread Starter [nicado](https://wordpress.org/support/users/nicado/)
 * (@nicado)
 * [4 years, 2 months ago](https://wordpress.org/support/topic/plugin-does-not-work-204/#post-15415962)
 * commercial hosting server, I will create a test environment to see.
 *  Thread Starter [nicado](https://wordpress.org/support/users/nicado/)
 * (@nicado)
 * [4 years, 2 months ago](https://wordpress.org/support/topic/plugin-does-not-work-204/#post-15432501)
 * after changing the theme the error changed
 *     ```
       Warning: Cannot modify header information - headers already sent by (output started at /home/*******/public_html/wp-includes/plugin.php:957) in /home/*******/public_html/wp-includes/functions.php on line 6821
   
       Warning: Cannot modify header information - headers already sent by (output started at /home/*******/public_html/wp-includes/plugin.php:957) in /home/*******/public_html/wp-admin/includes/misc.php on line 1310
   
       Fatal error: Uncaught Error: Undefined constant "‘woocommerce_email_order_meta’" in /home/*******/public_html/wp-content/plugins/woo-instant-notifications/admin/class-wcnotifications-instance.php:279 Stack trace: #0 /home/*******/public_html/wp-content/plugins/woo-instant-notifications/admin/class-wcnotifications-instance.php(250): WCNotifications_Instance->woocommerce_email_order_meta() #1 /home/*******/public_html/wp-content/plugins/woo-instant-notifications/admin/class-wcnotifications-instance.php(106): WCNotifications_Instance->convert_template() #2 /home/*******/public_html/wp-includes/class-wp-hook.php(309): WCNotifications_Instance->trigger(3287) #3 /home/*******/public_html/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters('', Array) #4 /home/*******/public_html/wp-includes/plugin.php(522): WP_Hook->do_action(Array) #5 /home/*******/public_html/wp-content/plugins/woocommerce/includes/class-wc-emails.php(170): do_action_ref_array('woocommerce_ord...', Array) #6 /home/*******/public_html/wp-includes/class-wp-hook.php(307): WC_Emails::send_transactional_email(Array, Object(Automattic\WooCommerce\Admin\Overrides\Order)) #7 /home/*******/public_html/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters('', Array) #8 /home/*******/public_html/wp-includes/plugin.php(474): WP_Hook->do_action(Array) #9 /home/*******/public_html/wp-content/plugins/woocommerce/includes/class-wc-order.php(373): do_action('woocommerce_ord...', 3287, Object(Automattic\WooCommerce\Admin\Overrides\Order)) #10 /home/*******/public_html/wp-content/plugins/woocommerce/includes/class-wc-order.php(222): WC_Order->status_transition() #11 /home/*******/public_html/wp-content/plugins/woocommerce/includes/admin/meta-boxes/class-wc-meta-box-order-data.php(635): WC_Order->save() #12 /home/*******/public_html/wp-includes/class-wp-hook.php(309): WC_Meta_Box_Order_Data::save(3287) #13 /home/*******/public_html/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters(NULL, Array) #14 /home/*******/public_html/wp-includes/plugin.php(474): WP_Hook->do_action(Array) #15 /home/*******/public_html/wp-content/plugins/woocommerce/includes/admin/class-wc-admin-meta-boxes.php(222): do_action('woocommerce_pro...', 3287, Object(WP_Post)) #16 /home/*******/public_html/wp-includes/class-wp-hook.php(309): WC_Admin_Meta_Boxes->save_meta_boxes(3287, Object(WP_Post)) #17 /home/*******/public_html/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters('', Array) #18 /home/*******/public_html/wp-includes/plugin.php(474): WP_Hook->do_action(Array) #19 /home/*******/public_html/wp-includes/post.php(4687): do_action('save_post', 3287, Object(WP_Post), true) #20 /home/*******/public_html/wp-includes/post.php(4789): wp_insert_post(Array, false, true) #21 /home/*******/public_html/wp-admin/includes/post.php(426): wp_update_post(Array) #22 /home/*******/public_html/wp-admin/post.php(227): edit_post() #23 {main} thrown in /home/*******/public_html/wp-content/plugins/woo-instant-notifications/admin/class-wcnotifications-instance.php on line 279
       ```
   
    -  This reply was modified 4 years, 2 months ago by [nicado](https://wordpress.org/support/users/nicado/).
 *  Plugin Author [Georgi Bakalski](https://wordpress.org/support/users/irdroid/)
 * (@irdroid)
 * [4 years, 2 months ago](https://wordpress.org/support/topic/plugin-does-not-work-204/#post-15432525)
 * Again, it is something specific (non-standard) to your installation.You can try
   Edit /wp-content/plugins/woo-instant-notifications/admin/class-wcnotifications-
   instance.php
 * and delete the line that contains :
 *  $this->placeholders[‘{woocommerce_email_order_meta}’] = $this->woocommerce_email_order_meta();
 *  Plugin Author [Georgi Bakalski](https://wordpress.org/support/users/irdroid/)
 * (@irdroid)
 * [4 years, 2 months ago](https://wordpress.org/support/topic/plugin-does-not-work-204/#post-15437837)
 * I guess, that the suggestion solved youe issues?
 *  Thread Starter [nicado](https://wordpress.org/support/users/nicado/)
 * (@nicado)
 * [4 years, 2 months ago](https://wordpress.org/support/topic/plugin-does-not-work-204/#post-15442946)
 * sorted out a lot thanks
 *  Plugin Author [Georgi Bakalski](https://wordpress.org/support/users/irdroid/)
 * (@irdroid)
 * [4 years, 2 months ago](https://wordpress.org/support/topic/plugin-does-not-work-204/#post-15458682)
 * I wonder what resolved the issue for you, because there is another user with 
   similar issue and your resolution may help him as well.

Viewing 9 replies - 1 through 9 (of 9 total)

The topic ‘plugin does not work’ is closed to new replies.

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 * 9 replies
 * 2 participants
 * Last reply from: [Georgi Bakalski](https://wordpress.org/support/users/irdroid/)
 * Last activity: [4 years, 2 months ago](https://wordpress.org/support/topic/plugin-does-not-work-204/#post-15458682)
 * Status: resolved