cannot upgrade to 12.04

[Greg Ruo]

update manager stops at the beginning when collecting preliminary information.
It seems my current distribution 10.04 is not complete, or something is missing, however up update-manager does not find any errors (this error appear only when I attempt distribution upgrade)

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: update-manager 1:0.134.12.1
ProcVersionSignature: Ubuntu 2.6.32-40.87-generic 2.6.32.57+drm33.23
Uname: Linux 2.6.32-40-generic i686
NonfreeKernelModules: fglrx
Architecture: i386
Date: Fri Mar 30 14:57:34 2012
GConfNonDefault:
 /apps/update-manager/check_new_release_ignore=
 /apps/update-manager/first_run=false
 /apps/update-manager/show_versions=false
 /apps/update-manager/window_size=(1269,943)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=ja_JP:ja:en_GB:en
 PATH=(custom, user)
 LANG=ja_JP.utf8
 SHELL=/bin/bash
SourcePackage: update-manager
VarLogDistupgradeTermlog:

[Greg Ruo (la1234uk)]

update-manager show problem for libmono-winforms2.0-cil and adobe-flashplugin (NO_PUBKEY).
I do not think this is the cause of the bug

[Brian Murray (brian-murray)]

Broken adobe-flashplugin:i386 Conflicts on flashplugin-installer [ i386 ] < 11.2.202.228ubuntu0.10.04. 1 -> 11.2.202.228ubuntu1 > ( multiverse/web )
  Considering flashplugin-installer:i386 3 as a solution to adobe-flashplugin:i386 2
  Holding Back adobe-flashplugin:i386 rather than change flashplugin-installer:i386
Done

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[dino99 (9d9)]

This version is no more supported