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

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)