APCu 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 APCu‘s variable cache as backend.


  1. You need to install and configure the APCu PHP extension.
  2. Download and extract the content of the archive file.
  3. 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.
  4. This plugin should now work without any further configuration. Check if it is listed under Plugins -> Installed Plugins -> Drop-ins.


“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/apcu. The APCu Object Cache Backend is not a regular WordPress plugin but a Drop-in. Therefore you cannot store it into the plugins directory.


6月 26, 2019
Apparently this plugin was forced in with the latest WordPress update. The problem is you might not know you even have it! I just went though two weeks of having my site go down over and over, 502 and 503 errors, EXTREMELY slow loading, even the admin side was not working... I've made over a dozen WordPress sites and I know the routine... I went through every plugin over and over, checked the theme, and fought with GoDaddy on three different days thinking it HAD to be their server.... Today, I happened to notice something I had never seen before. In addition to installed plugins, and the Must Use plugins, I saw an option for "Drop-in" plugins. What the hell is that? Lo and behold, I find something called "object-cache.php APCu Object Cache" You have to FTP in to your site and delete it from the main directory in order to get rid of it. My site was perfectly FINE once I removed it. What a massive, ridiculous hassle - for WordPress to give me this hidden plugin without my knowing. (I suggest you download a copy of object-cache.php before you delete it, in case you want to put it back... you never know...)
2月 22, 2019
We're unable to see updates on our website, we can't remove this plugin (the files don't exist where they should)...even deleting images still shows the image, regardless of flushing cache, changing browsers, etc... Use at your own risk, this plugin appears abandoned.


APCu Object Cache Backend はオープンソースソフトウェアです。以下の人々がこのプラグインに貢献しています。


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  • Maintenance Update
  • Compatibility with WordPress 5
  • Requires at least PHP 7.1


  • Minor code improvements
  • Compatibility with PHP 7.1 and WordPress 4.7


  • WordPress 4.4 support
  • Compatibility with PHP 7 and APCu 5


  • WordPress 4.3 support


  • initial version