This plugin hasn’t been tested with the latest 3 major releases of WordPress. It may no longer be maintained or supported and may have compatibility issues when used with more recent versions of WordPress.

XCache Object Cache Backend


Using this Plugin WordPress is able to store certain regular used elements into a persistent cache. Instead of computing complex operations over and over again on every single page request, its result is stored in memory once and from then on fetched directly from the cache on future page requests.

Such an object cache will reduce access to your database and speed up page loading.

This implementation uses XCache‘s variable cache as backend.


  1. You need to install and configure the XCache PHP extension.
  2. Make sure to set a size for the xcache.var_size directive (e.g. xcache.var_size=64M).
  3. Download and extract the content of the archive file.
  4. Upload the file object-cache.php of this plugin into your /wp-content/ directory. Note that this file needs to be stored directly into your content directory and not under the plugins directory.
  5. This plugin should now work without any further configuration. Check if it is listed under Plugins -> Installed Plugins -> Drop-ins.


“XCache is not configured correctly”

You will see this error message when either the xcache module is not loaded or the xcache.var_size directive is not set in your php.ini. If not configured, this setting defaults to 0 which disables the cache.

“Cannot redeclare wp_cache_add()…”

This error indicates that you likely have two copies of the object cache installed. Make sure you have put the file object-cache.php into your /wp-content/ directory only. Do not upload it to the /wp-content/plugins directory or any subdirectory like /wp-content/plugins/xcache. The XCache Object Cache Backend is not a regular WordPress plugin but a Drop-in. Therefore you cannot store it into the plugins directory.


Great plugin

Seems to work, I'm not getting any errors although a success message would be great

Fatal error

Fatal error: Cannot redeclare wp_cache_add() in /wp-content/plugins/xcache/object-cache.php on line 12
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Contributors & Developers

“XCache Object Cache Backend” is open source software. The following people have contributed to this plugin.



  • WordPress 4.3 support


  • Support WordPress Multisite setup
  • Add PHPUnit test to ensure compatibility
  • die() when people mistakenly try to activate this as a plugin, and provide a helpful message for where they should move the file. (from APC backend)
  • Fix incr() and decr() functions used. This fixes issues with BatCache and other plugins.
  • Fix $force option in get() function
  • Fix legacy use of reset() function


  • Fix type of $expire parameter
  • Compatibility with WordPress 3.7


  • Fix wrong logic when calling flush()
  • Verify compatibility with WordPress 3.6


  • Check if the variable cache is correctly configured and enabled
  • Clarify the installation instructions
  • added answers to “Frequently Asked Questions”


  • Compatibility with WordPress 3.5 API


  • Compatibility with XCache < 1.3 which does not have the xcache_unset_by_prefix function


  • Compatibility with WordPress 3.4 API



  • initial version