snapd package manager problem in ubuntu 16.04 , how to resolve?

Question

After this operation, 33.0 MB disk space will be freed.
Do you want to continue? [Y/n] y
(Reading database ... 329734 files and directories currently installed.)
Removing snapd (2.21~14.04) ...
Failed to stop snapd.autoimport.service: Unit snapd.autoimport.service not loaded.
dpkg: error processing package snapd (--remove):
 subprocess installed pre-removal script returned error exit status 5
Failed to get unit file state for snapd.refresh.timer: No such file or directory
snapd.refresh.timer is a disabled or a static unit, not starting it.
Failed to get unit file state for snapd.autoimport.service: No such file or directory
snapd.autoimport.service is a disabled or a static unit, not starting it.
Errors were encountered while processing:
 snapd
E: Sub-process /usr/bin/dpkg returned an error code (1)

Solution

Add exit 0 after shebang to /var/lib/dpkg/info/snapd.prerm.

Next remove a package dpkg --purge --force-all snapd.

Check you pkg sources for trusty rgrep 'xenial' /etc/apt, and remove all sources that my be correspond to inproper version of snapd.

Run apt-get update, and upgrade a system to be in consistent state.

Comments

[doug]

What are you doing with a trusty (14.04) backport package in xenial (16.04)?

[vskubriev]

Yeah. It is true, that this error appears when you install trusty snapd package in ubuntu xenial by a mistake.

[Jonny]

works like a charm!

[iWizard]

saved my day :)

[Donavan White]

Much useful information when debugging bad package installs.