error while updating (update manager)

did you try with terminal ?

try this code

sudo apt-get update && sudo apt-get upgrade

When you enter sudo apt-get update && sudo apt-get upgrade in terminal you get the following result:

Reading package lists... Error!
W: GPG error: http://extras.ubuntu.com precise Release: The following signatures were invalid: BADSIG 16126D3A3E5C1192 Ubuntu Extras Archive Automatic Signing Key <email address hidden>
W: GPG error: http://security.ubuntu.com precise-security Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <email address hidden>
W: GPG error: http://se.archive.ubuntu.com precise Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <email address hidden>
W: GPG error: http://se.archive.ubuntu.com precise-updates Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <email address hidden>
W: GPG error: http://se.archive.ubuntu.com precise-backports Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <email address hidden>
E: Encountered a section with no Package: header
E: Problem with MergeList /var/lib/apt/lists/se.archive.ubuntu.com_ubuntu_dists_precise_main_binary-amd64_Packages
E: The package lists or status file could not be parsed or opened.

The error message:

E:Encountered a section with no Package: header, E:Problem with MergeList /var/lib/apt/lists/se.archive.ubuntu.com_ubuntu_dists_precise_main_binary-amd64_Packages, E:The package lists or status file could not be parsed or opened.'

Please paste output of
uname -a; lsb_release -a

and one more thing you can try some commands

sudo apt-get clean
cd /var/lib/apt
sudo mv lists lists.old
sudo mkdir -p lists/partial
sudo apt-get clean
sudo apt-get update

This is what comes up when I enter: uname -a; lsb_release -a

Linux filip-HP-ProBook-4535s 3.2.0-20-generic #33-Ubuntu SMP Tue Mar 27 16:42:26 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu precise (development branch)
Release: 12.04
Codename: precise

Though with the other commands you posted it fixed the problem.
Follow the above commands and the Update Manager will hopefully work for those who have this problem.

Ok this 12.04 is not stable and you can not upgrade this because it is a
latest version of ubuntu which you already have... And still if you feeling
there is problem .. i suggest you to report a bug...and you can close this
question.. mark solved if you satisfied with my answer.. and if you have
other query please feel free to ask

Thanks
Jeet

From 2.3
On Mar 29, 2012 7:41 PM, "Filip Schultze" <
<email address hidden>> wrote:

Linux linuxc-Presario-V3000-RD996PA-UUF 3.0.0-16-generic #29-Ubuntu SMP Tue Feb 14 12:49:42 UTC 2012 i686 i686 i386 GNU/Linux
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 11.10
Release: 11.10
Codename: oneiric

any help

Help

did you tried above solution ?