Bug#867997: jessie->stretch, all apt clients break with /var/lib/dpkg/status realpath error

Alan Schwartz:
> Package: upgrade-reports
> Version: 9
> Severity: grave
> 
> Followed the Debian 9 release notes to upgrade a jessie i386 (686) machine
> to stretch. No apt sources except official debian ones. Following the apt-get
> dist-upgrade step, attempts to use apt-get, apt-cache, aptitude
> produce the following error:
> 
> # apt-get update
> Hit:1 http://ftp.us.debian.org/debian stretch-updates InRelease
> Ign:2 http://ftp.debian.org/debian stretch InRelease
> Get:3 http://security.debian.org stretch/updates InRelease [62.9 kB]
> Hit:4 http://ftp.debian.org/debian stretch Release
> Fetched 62.9 kB in 1s (38.2 kB/s)
> Reading package lists... Error!
> E: flAbsPath on /var/lib/dpkg/status failed - realpath (22: Invalid
> argument)
> E: Could not open file  - open (2: No such file or directory)
> E: Problem opening
> E: The package lists or status file could not be parsed or opened.
> 
> 
> Error persists after reboot of the system.
> 
> [...]

Hi,

Sorry to hear you had issues with the upgrade.

The problem you describe appears to be related to the release notes item
[5.3.2] (5.3.2.1 actually, but I cannot find the direct link to that).
The exact case with /var/lib/dpkg/status is not mentioned, but it could
be that there are some permissions on your system that forbit "_apt" to
access /var/lib/dpkg/status.

 * Could you please try to login in as the _apt user and check that it
   can read /var/lib/dpkg/status?
   - If it fails, please attempt to figure out where the permission
     fails (e.g. [dir-test])

 * If you have any policy framework enabled (SELinux or AppArmor),
   please check if any of these are forbidding the access.

Thanks,
~Niels

[5.3.2]:
https://www.debian.org/releases/stretch/amd64/release-notes/ch-information.en.html#apt-issues

[dir-test]: Example:

ls -ld / /var /var/lib /var/lib/dpkg /var/lib/dpkg/status