I have several WordPress (3.6) sites on the same server, all of these sites use the Memcached Object Cache - http://wordpress.org/plugins/memcached/ This plugin uses the memcache (no "d") extension.
root@linux10 [~]# php -m | grep mem memcache memcached
(Yep, both are installed)
root@linux10 [~]# php -v PHP 5.4.21 (cli) (built: Oct 29 2013 12:40:13)
2 sites work great with no issues. One particular site only works on the front end. The wp-admin fails to load with this error;
Fatal error: Class 'Memcache' not found in /home/townhous/public_html/wp-content/object-cache.php on line 372
L372 is $this->mc[$bucket] = new Memcache();
I know the object cache is working because the site uses a heavy and slow API, home page load times are 3+ seconds without the object-cache and milliseconds with the object-cache. Disabled the home page takes 3+ seconds and wp-admin works. Enabled and the homepage is fast but wp-admin doesn't work.
So, how can object-cache.php work for the front end and report a fatal error in the wp-admin?
Currently working around this issue with a nasty hack in load.php