After upgrading precise to quantal I am totally unable to run apt-get upgrade or apt-get -f install

sam@ubuntu-vm:~$ sudo apt-get upgrade
Reading package lists... Done
Building dependency tree       
Reading state information... Done
You might want to run 'apt-get -f install' to correct these.
The following packages have unmet dependencies:
 software-center : Depends: ubuntu-sso-client-gtk but it is not installable
                   Recommends: xz-lzma but it is not installable
E: Unmet dependencies. Try using -f.
sam@ubuntu-vm:~$ sudo apt-get -f install
Preparing to replace software-center 5.2.6 (using .../software-center_5.4.1.2_all.deb) ...
Unpacking replacement software-center ...
dpkg: error processing /var/cache/apt/archives/software-center_5.4.1.2_all.deb (--unpack):
 symbolic link '/usr/share/gnome/help/software-center/kn/software-center.xml' size has changed from 61 to 0
Errors were encountered while processing:
E: Sub-process /usr/bin/dpkg returned an error code (1)

I tried:

sudo apt-get remove --purge software-center software-center-aptdaemon-plugins to no avail

I tried:

sudo apt-get clean


sudo dpkg --configure -a
sudo apt-get -f install

I tried rebooting and no go.

Any tricks to getting my apt-get working again?

1 Answer 1


To work around this I uninstalled the offending packages, in my case:

sudo apt-get remove software-center ubuntu-desktop

Once removed I was able to re-install them.

I tracked down which to remove by chasing the dependency tree, first I tried removing software-center it complained about the ubuntu-desktop dependency, so I tried to add it.

I think a general similar approach should work for other errors like this.

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