Thread: Update manager problem WARNING: The following packages cannot be authenticated!

Just today itself my update manager was listing suggested updates with update-manager. But when I click install updates, its saying those updates were not genuine. I don't want do unauthenticated upgrade to my update-manager. Could you help me to resolve this issue?

Output of sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
The subsequent packages will be upgraded:
libpoppler-glib4 libpoppler5 libpython2.6 poppler-utils python2.6
python2.6-minimal update-manager update-manager-core
8 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 6,606kB of archives.
After this operation, 0B of additional disk space will be used.
Do you want to continue [Y/n]? Y
WARNING: The following packages cannot be authenticated!
libpython2.6 python2.6 python2.6-minimal update-manager update-manager-core
Install these packages without verification [y/N]? N
E: Some packages could not be legal

Try first the sudo apt-get update command to update the source listing. And after that update the ftp server key with sudo apt-key update command.

Thanks that resolved my question.