That's a bit odd that your webhost would not have an operating system listed in it's $_SERVER['SERVER_SOFTWARE'] variable (which is what offset 2 is in the $arg array in that function). However, to fix this, you can open plog-admin/plog-admin-functions.php and change line 1945 from this: $software_distro = $arg[2]; to this: $software_distro = isset($arg[2]) ? $arg[2] : '';