Hi, if the server runs with suPHP or FCGI, the files/folders permission have to be set to 644/755. Try this:
1. change permissions of all files in your installation directory to 644
2. change permissions of all directories in your installation directory to 755
3. change the settings in your config.local.php from
// Default permissions for newly created files and directories
define('DEFAULT_FILE_PERMISSIONS', 0666);
define('DEFAULT_DIR_PERMISSIONS', 0777);to
// Default permissions for newly created files and directories
define('DEFAULT_FILE_PERMISSIONS', 0644);
define('DEFAULT_DIR_PERMISSIONS', 0755);
My server/config files is already setup that way. It was set that way long ago.