Under Strict Mode, I get the following message while running W3 Total Cache on WP 3.8.1:
Strict Standards: Declaration of W3_Cache_Apc::delete() should be compatible with W3_Cache_Base::delete($key, $group = '') in <b>/Users/user/Documents/Sites/s3v11157/php/wp-content/plugins/w3-total-cache/lib/W3/Cache/Apc.php on line 15
I corrected it by changing the declaration of W3_Cache_Apc::delete() to accept a second optional argument, as it is declared in the parent class (W3_Cache_Base).
I changed line 125 on Apc.php to read:
function delete($key, $unused='') {
I reckon there should be other declarations with similar problems for the other cache methods as wel...
Regards!
I.-