Rudder

During install:

==> ubuntu_server: Setting up apache2-mpm-worker (2.2.22-1ubuntu1.9) ...
==> ubuntu_server:  * Starting web server apache2
==> ubuntu_server: apache2: Syntax error on line 234 of /etc/apache2/apache2.conf: Could not open configuration file /etc/apache2/conf.d/ncf-api-virtualenv.conf: No such file or directory
==> ubuntu_server: Action 'start' failed.
==> ubuntu_server: The Apache error log may have more information.
==> ubuntu_server:    ...fail!
==> ubuntu_server: invoke-rc.d: initscript apache2, action "start" failed.

[...]

==> ubuntu_server: Setting up ncf-api-virtualenv (3.0.5-precise1) ...
==> ubuntu_server: INFO: Creating the ncf-api-venv user...
==> ubuntu_server:  Done
==> ubuntu_server: INFO: Restarting Apache HTTPd...
==> ubuntu_server: dpkg: error processing ncf-api-virtualenv (--configure):
==> ubuntu_server:  subprocess installed post-installation script returned error exit status 1

And after:

$ service rudder-server-root restart
[...]
 * Starting web server apache2                                                                                                                                                                                                                                                                                                 Syntax error on line 17 of /etc/apache2/conf.d/ncf-api-virtualenv.conf:
Invalid command '<IfVersion', perhaps misspelled or defined by a module not included in the server configuration
Action 'start' failed.

Works after running:

a2enmod version