landscape-client fails when doing system upgrade

[Rigoberto Sanchez]

Doing a regular system upgrade but several systems failed. Upon inspecting and reproducing the same issue:

# apt update
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following packages were automatically installed and are no longer required:
  linux-headers-4.13.0-36 linux-headers-4.13.0-36-generic linux-image-4.13.0-36-generic linux-image-extra-4.13.0-36-generic
Use 'sudo apt autoremove' to remove them.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
1 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n] y
Setting up landscape-client (16.03-0ubuntu2.16.04.4) ...
install: missing file operand
Try 'install --help' for more information.
dpkg: error processing package landscape-client (--configure):
 subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
 landscape-client
E: Sub-process /usr/bin/dpkg returned an error code (1)

The looking at some logs:
# tail /var/log/dpkg.log
2018-05-17 10:50:35 startup packages configure
2018-05-17 10:50:35 configure landscape-client:amd64 16.03-0ubuntu2.16.04.4 <none>
2018-05-17 10:50:35 status half-configured landscape-client:amd64 16.03-0ubuntu2.16.04.4

The fastest workaround I've found is to purge landscape packages and re-installing..
# apt purge landscape-*
# apt install landscape-client

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Teluka (mateusz-p)]

Missing data_path is causing this.

Following resolves issue.

1. echo data_path = /var/lib/landscape/client >> /etc/landscape/client.conf
2. apt purge landscape-client
3. apt install landscape-client

[Sebastien Bacher (seb128)]

Thank you for your bug report, that looks like it already got reported as bug #1728681. Do you know how that line went missing?

[Teluka (mateusz-p)]

Can you confirm if data_path is a new parameter or was it present in default config in all previous versions of landscape-client ?