Title: unable activate cache
Last modified: December 12, 2018

---

# unable activate cache

 *  [lawix](https://wordpress.org/support/users/lawix/)
 * (@lawix)
 * [7 years, 6 months ago](https://wordpress.org/support/topic/unable-activate-cache/)
 * Hello all
 * No cache plugins work with my site under development ( w3 total cache, wp super
   cache, hummingbird …)
    When I activate and want to visit a page other than the
   index I have this error :
 * > PHP Fatal error: Call to a member function get() on null in /var/www/wp-includes/
   > cache.php on line 123, referer: [https://domain.fr/](https://domain.fr/)
 * It’s this function :
 *     ```
       function wp_cache_get( $key, $group = '', $force = false, &$found = null ) {
               global $wp_object_cache;
   
               return $wp_object_cache->get( $key, $group, $force, $found );
       }
       ```
   
 * Wordpress 4.9.8
    wp-config.php :
 *     ```
       define( 'WP_DEBUG', 'true' );
       define( 'WP_CACHE', 'true' );
       ```
   
 * Any idea ?
 * Thanks !
    Will

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

 *  Moderator [Steven Stern (sterndata)](https://wordpress.org/support/users/sterndata/)
 * (@sterndata)
 * Volunteer Forum Moderator
 * [7 years, 6 months ago](https://wordpress.org/support/topic/unable-activate-cache/#post-10979300)
 * What happens if you set WP_CACHE to false?
 * Also, true and false should not be in quotes/primes as they’re values, not strings.
 * `define( 'WP_DEBUG', true );` is correct, `'true'` is not.
 *  Thread Starter [lawix](https://wordpress.org/support/users/lawix/)
 * (@lawix)
 * [7 years, 6 months ago](https://wordpress.org/support/topic/unable-activate-cache/#post-10987998)
 * Hello,
 * If set to false, it’s work
 *     ```
       plugin write : Hummingbird could not write to the wp-config.php file. Please add the following line to the file manually: 
       define('WP_CACHE', true);
       ```
   
 * and if set “define( ‘WP_DEBUG’, true ),”
 * I have a blank page and this error log :
 * > PHP Fatal error: Call to a member function get() on null in /var/www/wp-includes/
   > cache.php on line 123, referer: [https://domain.fr/](https://domain.fr/)
 * Ps : true or ‘true’ do not change anything
    Thanks
 *  Moderator [Steven Stern (sterndata)](https://wordpress.org/support/users/sterndata/)
 * (@sterndata)
 * Volunteer Forum Moderator
 * [7 years, 6 months ago](https://wordpress.org/support/topic/unable-activate-cache/#post-10988636)
 * I recommend asking at [https://wordpress.org/support/plugin/hummingbird-performance#new-post](https://wordpress.org/support/plugin/hummingbird-performance#new-post)
   so the plugin’s developers and support community can help you with this.
 *  Thread Starter [lawix](https://wordpress.org/support/users/lawix/)
 * (@lawix)
 * [7 years, 6 months ago](https://wordpress.org/support/topic/unable-activate-cache/#post-10988797)
 * Ok but i have the same issues with other cache plugin like w3 total cache or 
   wp super cache
 *  Moderator [Steven Stern (sterndata)](https://wordpress.org/support/users/sterndata/)
 * (@sterndata)
 * Volunteer Forum Moderator
 * [7 years, 6 months ago](https://wordpress.org/support/topic/unable-activate-cache/#post-10988849)
 * Don’t try to install more than one plugin. Pick one and work with the developers
   of that one to see if they can see what might be wrong.

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

The topic ‘unable activate cache’ is closed to new replies.

 * In: [Fixing WordPress](https://wordpress.org/support/forum/how-to-and-troubleshooting/)
 * 5 replies
 * 2 participants
 * Last reply from: [Steven Stern (sterndata)](https://wordpress.org/support/users/sterndata/)
 * Last activity: [7 years, 6 months ago](https://wordpress.org/support/topic/unable-activate-cache/#post-10988849)
 * Status: not resolved

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