Title: Fatal error after plugin activation
Last modified: August 20, 2016

---

# Fatal error after plugin activation

 *  [JeffreyPia](https://wordpress.org/support/users/jeffreypia/)
 * (@jeffreypia)
 * [13 years, 3 months ago](https://wordpress.org/support/topic/fatal-error-after-plugin-activation/)
 * Upon plugin activation, the site front-end returns the following error:
    Fatal
   error: Call to undefined method WP_Query::is_main_query() in /wp-content/plugins/
   wordpress-seo/frontend/class-frontend.php on line 431
 * [http://wordpress.org/extend/plugins/wordpress-seo/](http://wordpress.org/extend/plugins/wordpress-seo/)

The topic ‘Fatal error after plugin activation’ is closed to new replies.

 * ![](https://ps.w.org/wordpress-seo/assets/icon-256x256.gif?rev=3419908)
 * [Yoast SEO - Advanced SEO with real-time guidance and built-in AI](https://wordpress.org/plugins/wordpress-seo/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/wordpress-seo/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/wordpress-seo/)
 * [Active Topics](https://wordpress.org/support/plugin/wordpress-seo/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/wordpress-seo/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/wordpress-seo/reviews/)

## Tags

 * [call to undefined method](https://wordpress.org/support/topic-tag/call-to-undefined-method/)
 * [fatal error](https://wordpress.org/support/topic-tag/fatal-error/)
 * [wp_query](https://wordpress.org/support/topic-tag/wp_query/)

 * 0 replies
 * 1 participant
 * Last reply from: [JeffreyPia](https://wordpress.org/support/users/jeffreypia/)
 * Last activity: [13 years, 3 months ago](https://wordpress.org/support/topic/fatal-error-after-plugin-activation/)
 * Status: not resolved