Updating to 11.10 from 11.04 fails at package ubuntu-minimal

[Excalibor]

After a full update of 11.04, tried to upgrade to 11.10 using update-manager but it crashed saying there was a critical problem while dealing with package ubuntu-minimal.

Last log lines are:

2011-10-14 17:53:41,483 DEBUG running doUpdate() (showErrors=True)
2011-10-14 17:56:09,936 DEBUG openCache()
2011-10-14 17:56:09,936 DEBUG failed to SystemUnLock() (E:Non está bloqueado)
2011-10-14 17:56:10,361 DEBUG /openCache(), new cache size 2258
2011-10-14 17:56:10,362 DEBUG needServerMode(): run in 'desktop' mode, (because of pkg 'ubuntu-desktop')
2011-10-14 17:56:10,362 ERROR No 'ubuntu-minimal' available/downloadable after sources.list rewrite+update
2011-10-14 17:57:02,379 DEBUG abort called
2011-10-14 17:57:02,383 DEBUG openCache()
2011-10-14 17:57:02,383 DEBUG failed to SystemUnLock() (E:Non está bloqueado)
2011-10-14 17:57:06,219 DEBUG /openCache(), new cache size 52808
2011-10-14 17:57:06,232 DEBUG enabling apt cron job

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: update-manager 1:0.150.3
ProcVersionSignature: Ubuntu 2.6.38-11.50-generic 2.6.38.8
Uname: Linux 2.6.38-11-generic x86_64
NonfreeKernelModules: nvidia wl
Architecture: amd64
Date: Fri Oct 14 17:57:16 2011
GConfNonDefault:
 /apps/update-manager/check_new_release_ignore=
 /apps/update-manager/first_run=false
 /apps/update-manager/show_details=true
 /apps/update-manager/window_size=(600,600)
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release amd64 (20101007)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=gl_ES:en
 PATH=(custom, user)
 LANG=gl_ES.UTF-8
 SHELL=/bin/bash
SourcePackage: update-manager
UpgradeStatus: Upgraded to natty on 2011-10-14 (0 days ago)

[Walter Garcia-Fontes (walter-garcia)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 873468 , so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Feel free to continue to report any other bugs you may find.