Running ubuntu 11 with nginx 1.0.5, php-fpm, apc 3.1.7 (stat=0).
Just attempted to update the w3tc plugin from 0.9.2.5 -> 0.9.2.8 and got this error,
Plugin failed to reactivate due to a fatal error. Warning: require_once(/wp-content/plugins/w3-total-cache/lib/W3/PluginProxy.php): failed to open stream: No such file or directory in /wp-content/plugins/w3-total-cache/lib/W3/Plugin/TotalCache.php on line 11 Fatal error: require_once(): Failed opening required '/wp-content/plugins/w3-total-cache/lib/W3/PluginProxy.php' (include_path='.:/usr/share/php:/usr/share/pear') in /wp-content/plugins/w3-total-cache/lib/W3/Plugin/TotalCache.php on line 11
I cleared the apc cache since with stat=0 its often an issue when making changes to w3tc as it stores configuration in php files on disk that would be cached by apc. After doing that I could reactivate w3tc to the new version but all previous settings were lost. Not good.
On a hunch I restored things back to before updating w3tc and changed the apc configuration so stat=1. Attempted the w3tc update again and this time it proceed without error.
Just posting this in case others might be affect by the same issue.