Bug#716880: apache2 upgrade failed

[Helmut Grohne <helmut@subdivi.de>]

Control: severity -1 important

Thanks for the detailed log, because it highlights the cause.

On Sun, Jul 14, 2013 at 01:51:55AM +0200, Vincent Lefevre wrote:
> Purging configuration files for apache2.2-common ...
> dpkg: warning: while removing apache2.2-common, directory '/usr/lib/cgi-bin' not empty so not removed
> dpkg: warning: while removing apache2.2-common, directory '/var/log/apache2' not empty so not removed
> dpkg: warning: while removing apache2.2-common, directory '/var/www' not empty so not removed

You are likely using --purge-unused something similar causing the no
longer needed package apache2.2-common to be purged. It is removed and
purged very early during the upgrade. Unfortunately this package
contains your apache configuration. At the time apache2 is upgraded, it
notices there is no configuration left and fails. The issue here is not
that the upgrade fails, but that your configuration vanishes. Papering
over purged configuration in apache2's postinst is not a solution. As a
first measure don't upgrade with --purge-unused. I am downgrading the
severity, because it only happens when you purge packages during
upgrade.

As far as I can tell the only way to fix this issue is to introduce a
transitional apache2.2-common package containing no files. apache2 would
need to depend on apache2.2-common for one release (skipping a release
is not supported). This would ensure that apache2.2-common is not purged
during upgrades. After one release the transitional package can be
dropped.

Helmut