"apt-get update" failure

Using Kali Linux 2.0
I get this error msg when entering the listed command.
Does it mean it is asking to install the rolling version??
:confused:

]E: GPG error: http://P kali-rolling Release: The following signatures were invalid: NODATA 1 NODATA 2[/B]


root@Tau:~# apt-get update
Get:1 http://P kali-rolling Release.gpg
Get:2 http://P kali-rolling Release
Ign http://P kali-rolling Release
E: GPG error: http://P kali-rolling Release: The following signatures were invalid: NODATA 1 NODATA 2
root@Tau:~# ^

Kali Sana's repositories are retired...
http://docs.kali.org/general-use/kal...t-repositories
Time to go for kali rolling :)

i installed Sana like.. 6 months ago and made the second update a week ago and it worked :)