Upgrading a Xen Virtual Private Server from Ubuntu 7.04 (Feisty) to 7.10 (Gutsy)

For the last two years, I have been running a Xen based VPS which has Ubuntu server on it. Up to last week, it was running Feisty Fawn (7.04), and it was time to upgrade it to Gutsy Gibbon (7.10), the latest Ubuntu version.

The upgrade had some complications, so I am documenting them here in case someone has the same problem.

Procedure for upgrade

On Debian and earlier versions of Ubuntu, the procedure for upgrading consisted of entering the commands:

# aptitude update && aptitude dist-upgrade 

However, starting with Gutsy, Ubuntu has a separate update manager. In order to use that, you run the following commands:

# aptitude install update-manager-core
# do-release-upgrade

Update failure

On the Xen VPS, there are some bugs that causes the upgrade to fail after doing a whole lot of things.

So I try running the normal update:

# aptitude update

Which aborts with a message to run the following command.

# dpkg --configure -a

When you try to run the above command, you get lots of errors, many of them segmentation faults, and then an error saying that too many errors happened.

Troubleshooting the failure 

In order to try to troubleshoot this, I do --configure for just one package:

# dpkg --configure  apache2-mpm-prefork

This says that a package that it depends on is not configured, so I try the dependency:

# dpkg --configure  apache2.2-common

And I get an error saying that in turn, this depends on another package, so I try that:

# dpkg --configure procps

This gives the segmentation fault ...

Googling for a solution

After some Google, I found some clues. Initially, I thought it is 140739, but downgrading did not work.

Then, I searched more and found a Xen specific problem, 152664, which seemed to fit the bill.

Deborphan to the rescue

The solution is to install and run deborphan, remove the problem packages, and then do a proper --configure.

But, that VPS does not have deborphan installed, and installing it via aptitude fails because of the original problem we are trying to solve. So we are in a catch-22 situation.

What can one do?
You can use the dpkg command directly, but you have to find and download the package.

To do this: you go to the deborphan package, which depends on dialog.

Then download them: 

# wget http://launchpadlibrarian.net/5146737/deborphan_1.7.23_i386.deb
# wget http://launchpadlibrarian.net/8022814/dialog_1.1-20070604-1_i386.deb

Install dialog, then deborphan:

# dpkg -i dialog_1.1-20070604-1_i386.deb
# dpkg -i deborphan_1.7.23_i386.deb

We now run deborphan, and pipe the output to aptitude with remove and automatic answering Yes.

# deborphan | xargs aptitude -y remove

Now, we can configure all packages:

# dpkg --configure -a

That completes successfully, at last ...

And after that, we run normally:

aptitude update && aptitude safe-upgrade

Hope this is helpful to someone, since I spend a couple of hours scraching my head on it ...