title: "PHP Fatal error: Class 'Memcache' not found" occurred in object-cache.php of wordpress even after installed memcache extension
body: <p>I tried to enable object cache for wordpress by using Memcache. And I put <code>object-cache.php</code> into /wp-content/, which I get from <a href="https://wordpress.org/plugins/memcached/" rel="nofollow">Memcached Object Cache</a> plugin.</p>
  
  <p>And then <code>PHP Fatal error:  Class 'Memcache' not found</code> occurred. So I install memcache extension by executing <code>sudo yum -y install php-pecl-memcache</code> and <code>sudo service httpd restart</code>. But nothing changed.</p>
  
  <p>I also tried to install <code>php-pecl-memcached</code>, not <code>php-pecl-memcache</code>. But nothing had changed.</p>
  
  <p>I confirmed that <code>/etc/php.d/memcache.ini</code> file existed and <code>extension=memcache.so</code> is loaded in the file.</p>
  
  <p>Please give me an advice to solve this.</p>
  
  <p>When I tried that for new EC2 instance, it worked well. So I guess my environment is preventing in some ways. Any ideas?</p>