[Bug 346386] Re: [MASTER] Update fails with invalid package files with "Encountered a section with no Package: header"

[Manfred Hampl]

@Steven and others:
The package management programs store information about available packages, their versions, and their sources in some files on your computer.
The problem that you encounter is caused by wrong contents in some of these files.
The recently published changes in the apt package prevent that running a package management update command creates new files with wrong contents, but they do not solve the problem if you have already such situation on your system.

To clean up this status please see
https://answers.launchpad.net/ubuntu/+faq/1591

Either run:
sudo rm -rf /var/lib/apt/lists
sudo mkdir /var/lib/apt/lists
sudo mkdir /var/lib/apt/lists/partial

or perform a full package management troubleshooting as described in
https://help.ubuntu.com/community/PackageManagerTroubleshootingProcedure

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https://bugs.launchpad.net/bugs/346386

Title:
  [MASTER] Update fails with invalid package files with "Encountered a
  section with no Package: header"

Status in “apt” package in Ubuntu:
  Fix Released
Status in “apt” source package in Natty:
  Fix Released
Status in “apt” package in Debian:
  Fix Released

Bug description:
  Binary package hint: adept-updater

  Pertinent data printed when attempting to run Updater as follows:

  An unresolvable problem occurred while initializing the package
  information.

  Please report this bug against the 'update-manager' package and
  include the following error message:

  'E:Encountered a section with no Package: header, E:Problem with
  MergeList /var/lib/apt/lists/us.archive.ubuntu
  .com_ubuntu_dists_intrepid_universe_binary-amd64_Packages, E:The
  package lists or status file could not be parsed or opened.'

  WORKAROUND:
  Remove problematic files from /var/lib/apt/lists/ and rerun apt-get update.

  In the event that one is connected to a network with a proxy server
  that returns html pages (like a web page requesting you to login) and
  not package list files.   Those html files will get downloaded to
  /var/lib/apt/lists/ and prevent someone from using a package manager
  until the problem html pages are removed.

  TEST CASE:
  1) Ensure /etc/apt/sources.list points to archive.ubuntu.com
  2) Setup proxy server to block access to archive.ubuntu.com and return something like http://people.canonical.com/~brian/tmp/not-packages.html
  3) Execute 'sudo apt-get update' in a terminal
  4) Observe the following:
  'E: Encountered a section with no Package: header
   E: Problem with MergeList /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_natty_main_binary-amd64_Packages
   E: The package lists or status file could not be parsed or opened.'
  5) Try 'apt-cache policy apt' and be sad that it doesn't work
  6) run 'sudo rm /var/lib/apt/lists/*Packages' to clear the error.

  With the proposed package installed repeat steps 1 to 3.
  4) Observe the following:
  ''Get:1 http://archive.ubuntu.com oneiric InRelease [189 B]
  Ign http://archive.ubuntu.com oneiric InRelease
  E: GPG error: http://archive.ubuntu.com oneiric InRelease: The following signatures were invalid: NODATA 1 NODATA 2'
  5) Try 'apt-cache policy apt' and be happy that it works

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