When loading and running XCache (either version 1,3, 1.2, 1.2.1, 1.2.2, 1.0.3 or any other future or earlier versions) as PHP Zend extension as PHP opcode cacher to speed up a website delivery performance, the following error may occur:

XCache requires Zend Engine API version 220051025.
The Zend Engine API version 220060519 which is installed, is newer.
Contact mOo at http://xcache.lighttpd.net for a later version of XCache.


Or,

XCache requires Zend Engine API version 220060519.
The Zend Engine API version 220090626 which is installed, is newer.
Contact mOo at http://xcache.lighttpd.net for a later version of XCache.

The error happens when the web server such as Apache HTTPD or lighttpd trying to load XCache as defined and configured in PHP.INI, causing the XCache module not loaded and not implemented. The problem is, especially for system already running XCache v1.3.0, there is no newer or later version of XCache to download and install. In addition, there is no error been logged by sub-systems either.

The main cause for the error is because of outdated build of XCache (not related to its actual version though), that mostly happens when user upgrades PHP version. When compiling and building XCache, it’s been associated with the version of Zend Engine API that exists on the system at the time. When PHP is updated or upgraded, the Zend Engine API is updated too, causing XCache module to fail as the version no longer matched.

The solution for the Zend Engine API version is newer error is pretty simple. Just download, compile and install XCache again will fix and resolve the issue permanently (until new PHP major version update).

Note: The path to the installed xcache.so file (e.g. zend_extension = /usr/local/lib/php/extensions/no-debug-non-zts-xxxxxxxx/xcache.so) will likely have changed, so remember to edit the PHP.INI to reflect the new path.