Go to the /etc/pam.d directory.
Open the file common-session-noninteractive in an editor.
Look for the following line:
session required pam_unix.so
Above this line, add the following:
session [success=1 default=ignore] pam_succeed_if.so service in cron quiet use_uid
Save the file and exit.
and that should do it!
Hope this helps :)
