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.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.