Zentyal - Bandwidth Monitor fails to install

[jmassagues@…]

Component zentyal-bwmonitor fails to install. The Web UI recommends to run dpkg --configure -a. Doing so shows the following lines:

Setting up zentyal-bwmonitor (2.1.2) ...
Error loading class: EBox::BWMonitor error: Base class package "EBox::FirewallObserver" is empty.
    (Perhaps you need to 'use' the module which defines that package first,
    or make that module available in @INC (@INC contains: /etc/perl /usr/local/lib/perl/5.10.1 /usr/local/share/perl/5.10.1 /usr/lib/perl5 /usr/share/perl5 /usr/lib/perl/5.10 /usr/share/perl/5.10 /usr/local/lib/site_perl .).
 at /usr/share/perl5/EBox/BWMonitor.pm line 21
BEGIN failed--compilation aborted at /usr/share/perl5/EBox/BWMonitor.pm line 25.
Compilation failed in require at (eval 72) line 2.
BEGIN failed--compilation aborted at (eval 72) line 2.
dpkg: error processing zentyal-bwmonitor (--configure):
 subprocess installed post-installation script returned error exit status 255
Errors were encountered while processing:
 zentyal-bwmonitor

I took the following actions:

1. purge the zentyal-bwmonitor component
2. install the zentyal-firewall component
3. enable the firewall in the Web GUI

After that I could install the zentyal-bwmonitor component. Most likely the root cause is an undeclared dependency in zentyal-bwmonitor on zentyal-firewall.

[jacalvo@…]

(In [22492]) NN: Fixed crash when zentyal-firewall is not installed depending on it (closes #3051)