I upgraded to 11.04 today. I had some problems when the system froze with 2 minutes to go; I was forced to do a hard reboot, but the system appeared to work OK. (described here: https://askubuntu.com/questions/40295/distribution-upgrade-froze-my-system)

As the system hadn't been cleaned up before rebooting, I ran Computer Janitor, but had to stop it when I saw it was deleting things I needed to keep (e.g. Faenze icons vanished). Since then I have been unable to install anything via apt-get, Synaptic or Software Centre. I can add PPAs, but attempting to install anything returns the following message:

E: Sub-process /usr/bin/dpkg returned an error code (1)

The only way I can install anything is by downloading the deb and installing manually.

Trying to install with the Software Centre causes a window to open saying "An unhandled error occurred). Clicking on "details" reveals the following:

Traceback (most recent call last): File "/usr/lib/python2.7/dist-packages/aptdaemon/worker.py", line 961, in simulate trans.unauthenticated = self._simulate_helper(trans) File "/usr/lib/python2.7/dist-packages/aptdaemon/worker.py", line 1085, in >_simulate_helper return depends, self._cache.required_download, \ File "/usr/lib/python2.7/dist-packages/apt/cache.py", line 226, in required_download pm.get_archives(fetcher, self._list, self._records) SystemError: E:I wasn't able to locate file for the rec-applet package. This might mean >you need to manually fix this package.

However, when I try to repost the problem, another window opens with the title "Problem in aptdaemon" and

The problem cannot be reported:

You have some obsolete package versions installed. Please upgrade the following >packages and check if the problem still occurs:


EDIT - I tried Jordy's solution. When I then checked for local or obsolete packages in Synaptic, one was marked in red and marked for removal (rec-applet). When I attempt to remove it, I get the message:

E: rec-applet: subprocess installed post-removal script returned error exit status 1

It's as if that was blocking everything else, but there doesn;t seem to be a way of removing it.

EDIT 2 - I remived the offending package following the instructions here: http://www.khattam.info/solved-subprocess-pre-removal-script-returned-error-exit-status-2-error-2009-08-04.html

I feel a bit dirty but it did work, and no need to reinstall the OS.

  • It is not my usually used advice but I would seriously consider reinstalling your OS. This 'I had some problems when the system froze with 2 minutes to go; is not good and you might run into another problem after fixing this one. I support your effort though in trying to fix it without reinstalling though!
    – Rinzwind
    May 5, 2011 at 13:43

2 Answers 2


Probably you have broken packages, type: sudo dpkg --configure-a


Regarding this specifically: E: Sub-process /usr/bin/dpkg returned an error code (1)

I found a possible solution mentioned in this message here

  • Try apt-get -f install to force an install of the files that didn't get loaded because of the error. Then try apt-get upgrade again, apt-get -f install back and forth until only the package that has the error is left.

It is a post based on Debian but this also is valid for Ubuntu.

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