Title: Cannot be activated, PHP fatal error.
Last modified: March 11, 2024

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# Cannot be activated, PHP fatal error.

 *  Resolved [Malae](https://wordpress.org/support/users/malae/)
 * (@malae)
 * [2 years, 2 months ago](https://wordpress.org/support/topic/cannot-be-activated-php-fatal-error/)
 * Hello,
 * WordPress 6.4.3 PHP 8.0 installed. The plugin cannot be activated.
   `PHP Fatal
   error: Cannot redeclare wp_cache_add() (previously declared in /wp-includes/cache.
   php:41) in /wp-content/plugins/memcached/object-cache.php on line 19`

Viewing 1 replies (of 1 total)

 *  Moderator [Dion Hulse](https://wordpress.org/support/users/dd32/)
 * (@dd32)
 * Meta Developer
 * [2 years, 2 months ago](https://wordpress.org/support/topic/cannot-be-activated-php-fatal-error/#post-17534314)
 * This plugin isn’t a plugin per-se, it’s a Object cache drop-in, and requires 
   additional steps in order to use it. Including having a separate Memcache server
   and configuration in `wp-config.php` as appropriate.
 * Some installation instructions are available [in the Installation tab](https://wordpress.org/plugins/memcached/#installation)
   on the plugin page.
 * This “plugin” can’t be used as a plugin, as it’s required to be loaded before
   WordPress fully inialises, and before it loads plugins.
 * I’ve [opened an issue](https://github.com/Automattic/wp-memcached/issues/157)
   to have the plugin activation step lead to something more helpful than a fatal
   error.

Viewing 1 replies (of 1 total)

The topic ‘Cannot be activated, PHP fatal error.’ is closed to new replies.

 * ![](https://s.w.org/plugins/geopattern-icon/memcached.svg)
 * [Memcached Object Cache](https://wordpress.org/plugins/memcached/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/memcached/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/memcached/)
 * [Active Topics](https://wordpress.org/support/plugin/memcached/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/memcached/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/memcached/reviews/)

## Tags

 * [PHP Fatal error](https://wordpress.org/support/topic-tag/php-fatal-error/)

 * 1 reply
 * 2 participants
 * Last reply from: [Dion Hulse](https://wordpress.org/support/users/dd32/)
 * Last activity: [2 years, 2 months ago](https://wordpress.org/support/topic/cannot-be-activated-php-fatal-error/#post-17534314)
 * Status: resolved