i did the upgrade with: sudo do-release-upgrade -d

[Steven Stratford]

I tried to upgrade von 12.04 to 14.04

i did :

sudo apt-get install update-manager-core
sudo do-release-upgrade -d

I got the answer:

An unresolvable problem occurred while calculating the upgrade.

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

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: update-manager 1:0.156.14.13
ProcVersionSignature: Ubuntu 3.11.0-18.32~precise1-generic 3.11.10.4
Uname: Linux 3.11.0-18-generic x86_64
NonfreeKernelModules: btrfs raid6_pq zlib_deflate xor ufs qnx4 hfsplus hfs minix ntfs msdos jfs xfs reiserfs nls_iso8859_1 rfcomm bnep snd_hda_codec_realtek snd_hda_codec_hdmi parport_pc snd_hda_intel snd_hda_codec ppdev snd_hwdep eeepc_wmi asus_wmi snd_pcm joydev uvcvideo sparse_keymap snd_seq_midi snd_rawmidi snd_seq_midi_event snd_seq videobuf2_core videodev snd_timer btusb psmouse snd_seq_device videobuf2_vmalloc bluetooth snd videobuf2_memops sp5100_tco serio_raw soundcore i2c_piix4 snd_page_alloc k10temp mac_hid arc4 brcmsmac mac80211 bcma brcmutil cfg80211 nfsd cordic nfs_acl auth_rpcgss nfs lp fscache parport lockd binfmt_misc sunrpc ext2 sdhci mmc_block dm_crypt vesafb usb_storage r8169 ahci mii libahci video wmi
ApportVersion: 2.0.1-0ubuntu17.6
Architecture: amd64
Date: Fri Apr 18 03:59:11 2014
EcryptfsInUse: Yes
GsettingsChanges:
 com.ubuntu.update-manager first-run false
 com.ubuntu.update-manager launch-time 1397785523
 com.ubuntu.update-manager window-height 500
 com.ubuntu.update-manager window-width 600
InstallationMedia: Ubuntu 12.04.1 LTS "Precise Pangolin" - Release amd64 (20120822.4)
MarkForUpload: True
PackageArchitecture: all
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: update-manager
Symptom: ubuntu-release-upgrader-core
UpgradeStatus: Upgraded to precise on 2014-04-18 (0 days ago)