Comment 70 for bug 153980

from /var/log/dist-upgrade/main.log :

2009-02-24 21:56:48,234 INFO release-upgrader version '0.81' started
2009-02-24 21:56:54,230 DEBUG lsb-release: 'feisty'
2009-02-24 21:56:54,231 DEBUG _pythonSymlinkCheck run
2009-02-24 21:56:57,190 DEBUG checkViewDepends()
2009-02-24 21:56:57,191 DEBUG getRequiredBackports()
2009-02-24 21:56:59,082 ERROR IOError in cache.update(): 'Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/feisty-backports/main/debian-installer/binary-i386/Packages.gz 404 Not Found
'. Retrying (currentRetry: 0)
2009-02-24 21:57:01,108 ERROR IOError in cache.update(): 'Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/feisty-backports/main/debian-installer/binary-i386/Packages.gz 404 Not Found
'. Retrying (currentRetry: 1)
2009-02-24 21:57:03,145 ERROR IOError in cache.update(): 'Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/feisty-backports/main/debian-installer/binary-i386/Packages.gz 404 Not Found
'. Retrying (currentRetry: 2)
2009-02-24 21:57:03,145 ERROR doUpdate() failed complettely
2009-02-24 21:57:10,852 ERROR Can not find backport 'release-upgrader-apt'

so - tried adding :
# 91.189.88.35 is old-releases.ubuntu.com
91.189.88.35 us.archive.ubuntu.com
 to /etc/hosts to try and fool it ...

did not work - so tried a command line wget to test:
# wget http://us.archive.ubuntu.com/ubuntu/dists/feisty-backports/main/debian-installer/binary-i386/Packages.gz
--21:59:35-- http://us.archive.ubuntu.com/ubuntu/dists/feisty-backports/main/debian-installer/binary-i386/Packages.gz
           => `Packages.gz'
Resolving us.archive.ubuntu.com... 91.189.88.35
Connecting to us.archive.ubuntu.com|91.189.88.35|:80... connected.
HTTP request sent, awaiting response... 404 Not Found
21:59:35 ERROR 404: Not Found.

same in browser - using old-releases works, using us.archive fails even with hosts entry.
tried ftp hoping to get around apache vhosts, same problem.

so - just speculating - it appears that the fix is to fix that actual package
the file is apparently from: .../gutsy/main/dist-upgrader-all/current/gutsy.tar.gz
offending file is: prerequists-sources.list
change line:
deb http://${countrymirror}archive.ubuntu.com/ubuntu feisty-backports main/debian-installer
to:
deb http://old-releases.ubuntu.com/ubuntu feisty-backports main/debian-installer