On some servers when you are trying to add/delete plugins using "Upgrade Automatically" option (via ftp) you might be notified with following message:
Upgrade Plugin
Unable to locate WordPress Content directory (wp-content).
The reason for this is that the ftp client is not allowed to access the path defined as absolute path (ABSPATH) in wordpress configuration. More details can about this problem can be found in this post http://wordpress-hints.blogspot.com/2011/01/upgrade-wordpress-unable-to-locate.html .
