Pierre Schmitz

Looking at your error again makes me conclude that this is not related to the APCu plugin at all. It does not declare a WP_Object_Cache.

I’d say first check if there any other files than cache.php declaring this file. E.g.:
grep -riEl 'class\s+WP_Object_Cache' <your-wp-folder>

Otherwise something includes cache.php twice. Maybe batcache; try disabling it.

See https://www.ads-software.com/plugins/apcu/faq/

Also check if you have other Caching Plugins installed.

This has to go into your php.ini file.

If APCu is not available you should get a 503 response with the following message: “APCu is not configured correctly. Please refer to https://www.ads-software.com/extend/plugins/apcu/installation/ for instructions.”

Unfortunately it is not straight forward to implement a fallback when APCu module is not loaded. The cache.php is not loaded when an object-cache.php file is available.

EDIT: I think it actually can be done (in a dirty way) but I am not sure it should be done. Silently falling back to no caching when APCu does not work will hide configuration issues.

Yes, this should work fine. I just updated the supported WordPRess version.

That should not happen. Any details on your benhmark setup would be appreciated. I’d look into this then.

You should install the xcache package from your distribution if you don’t know how to build it from source.

Where exactly got you stuck during the install process? The archive contains three files.

Paragaph 4 of the install instructions tells you where to put which file.

Thanks for the hint. I’ll link the other plugin post for reference here: https://www.ads-software.com/support/topic/conflict-with-xcache-object-cache-backend

I’ll mark this as resolved then.

Hi, did you get any feedback from the author of the other plugin? I would need to debug that other plugin and I cannot tell when I’ll have time.

I would guess that the plugin does not invalidate the cache at some point.

This is not a typical WP plugin. Do not copy it into the plugin folder. See the Installation Instructions for details.

I did not try “WP Super Cache”. But as the XCache plugin simply is an implementation of the WordPress object cache API, every other plugin should work fine unless it does really strange things.

I suggest to just try it.

I am sorry, but I was not able to reproduce this issue. (using PHP 5.4.14 and XCache 3.0.1)

I have tested a new install of 3.5 and the update to 3.6 without any problems. I probably need more details here.

These files should not be in the plugin directory in the first place. I’ll try to document that clearer.

You seem to have two different object cache implementations installed. The one in the plugins folder is also in the wrong place.

Please read https://www.ads-software.com/extend/plugins/xcache/installation/