If you receive the above error message this will mean that things like import / export won’t work as they can’t read or write files to the system, this will also cause problems for most of our themes as they dynamically write styles files from your settings.
You should follow the above links and read the page which explains the problems http://codex.wordpress.org/Editing_wp-config.php#WordPress_Upgrade_Constants
This problem is usually fixed by following the below steps:
1. Open your wp-config.php file located in the root of your website (you will need to do this via FTP or some other file manager)
2. Somewhere near the bottom of the file, usually just below the line “define(‘WP_DEBUG’, false);” try adding the line:
“define( ‘FS_METHOD’, ‘direct’ );” and then upload and refresh your admin area to see if the message has disappeared. If the message does not disappear after a refresh try changing the line you added and specifically the ‘direct’ to the following and each time try uploading and refreshing to see if it fixes it: “ssh2“, “ftpext“, or “ftpsockets“.
3. If #2 did not fix your problem try adding these two lines:
define( ‘FTP_USER’, ‘username’ );
define( ‘FTP_PASS’, ‘password’ );
Replacing the ‘username’ and ‘password’ with your FTP username and password, again try uploading and refreshing to see if it fixes the problem, if the problem persists repeat #2 now that you have the ftp user/pass defined.
The above three steps should fix the majority of problems, if not then please post in our support forum and a member of our support staff will assist.