Comment 29 for bug 551782

I have the same problem:

sudo do-release-upgrade -d
Checking for a new ubuntu release
Done Upgrade tool signature
Done Upgrade tool 4s
Done downloading
extracting 'lucid.tar.gz'
authenticate 'lucid.tar.gz' against 'lucid.tar.gz.gpg'
tar: Removing leading `/' from member names

Reading cache

Checking package manager
Reading package lists: Done
Reading state information: Done
Reading state information: Done
Reading state information: Done
Done downloading
Reading package lists: Done
Reading state information: Done
Reading state information: Done
Reading state information: Done

Updating repository information
WARNING: Failed to read mirror file

Third party sources disabled

Some third party entries in your sources.list were disabled. You can
re-enable them after the upgrade with the 'software-properties' tool
or your package manager.

Done downloading

Checking package manager
Reading package lists: Donem lucid/partner Packages: 94 ges: 94
Reading state information: Done
Reading state information: Done
Reading state information: Done

Calculating the changes

Calculating the changes

Could not calculate the upgrade

An unresolvable problem occurred while calculating the upgrade:
E:Unable to correct problems, you have held broken packages.

This can be caused by:
* Upgrading to a pre-release version of Ubuntu
* Running the current pre-release version of Ubuntu
* Unofficial software packages not provided by Ubuntu

If none of this applies, then please report this bug against the
'update-manager' package and include the files in
/var/log/dist-upgrade/ in the bug report.

Restoring original system state

Aborting
Reading package lists: Donermic/main Packages: 94 94 93 es: 92
Reading state information: Done
Reading state information: Done
Reading state information: Done