Upgrade to 12.10 failed before "cleaning up" stage because it couldn't get exclusive lock

[Dawid Wróbel]

During my upgrade to 12.10 yesterday, the upgrade failed just before the "cleaning up" stage and an "Unable To get Exclusive Lock" error was shown on the screen. "ps ax|grep apt" has shown aptd running in the background.
I suspect that this was unattended upgrades that got started up, because I had it set up for automatically applying critical upgrades.

Now for what it's worth, before I managed to start the upgrade process, I couldn't even start the "update-manager -d" for the same reason (aptd in the background) and then it had failed two times to go past the initial stage: once for the very same reason ("Unable To get Exclusive Lock", had to kill aptd), second time because I was out of disk space. After I dealt with disk space, I had to do "mv /etc/apt/sources.list.save /etc/apt/sources.list" and "apt-get update" because apparently the state was not rolled back after the update-manager failed (I had update-manager popping up and showing a list of 12.10 packages to install over 12.04 ones).
The third time I managed to run it, but it failed half way through as I explained in the first paragraph.

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: update-manager 1:0.173
ProcVersionSignature: Ubuntu 3.5.0-14.19-generic 3.5.3
Uname: Linux 3.5.0-14-generic x86_64
ApportVersion: 2.5.1-0ubuntu7
Architecture: amd64
Date: Sat Sep 15 19:26:47 2012
GsettingsChanges:
 b'com.ubuntu.update-manager' b'launch-time' b'1331248512'
 b'com.ubuntu.update-manager' b'window-height' b'500'
 b'com.ubuntu.update-manager' b'window-width' b'600'
InstallationMedia: Kubuntu 10.10 "Maverick Meerkat" - Beta amd64 (20100902.1)
PackageArchitecture: all
SourcePackage: update-manager
UpgradeStatus: Upgraded to quantal on 2012-09-14 (0 days ago)