Comment 0 for bug 1574250

$ lsb_release -rd
Description: Ubuntu 16.04 LTS
Release: 16.04

$ apt-cache policy icingaweb2
icingaweb2:
  Installed: 2.1.0-1ubuntu1
  Candidate: 2.1.0-1ubuntu1
  Version table:
 *** 2.1.0-1ubuntu1 500
        500 http://us.archive.ubuntu.com/ubuntu xenial/universe amd64 Packages
        500 http://us.archive.ubuntu.com/ubuntu xenial/universe i386 Packages
        100 /var/lib/dpkg/status

I've installed Ubuntu 16.04 from the latest ISO and did a "apt update && apt upgrade" to be certain I use the latest updates.
Then I've installed icingaweb2 via "sudo apt install icingaweb2":

What was still missing after that was mod-php (the issue was a white page when browsing http://<hostname>/icingaweb2/). Thus, to get it working I had to run "sudo apt install libapache2-mod-php".

With that the white page has been resolved but then I got the following error:

<b>Warning</b>: Uncaught ErrorException: require_once(Zend/Loader/Autoloader.php): failed to open stream: No such file or directory in /usr/share/php/Icinga/Application/ClassLoader.php:276
Stack trace:
#0 /usr/share/php/Icinga/Application/ClassLoader.php(276): Icinga\Application\ApplicationBootstrap->Icinga\Application\{closure}(2, 'require_once(Ze...', '/usr/share/php/...', 276, Array)
#1 /usr/share/php/Icinga/Application/ClassLoader.php(276): require_once()
#2 /usr/share/php/Icinga/Application/ClassLoader.php(294): Icinga\Application\ClassLoader->requireZendAutoloader()
#3 [internal function]: Icinga\Application\ClassLoader->loadClass('Zend_Controller...')
#4 /usr/share/php/Icinga/Web/Request.php(13): spl_autoload_call('Zend_Controller...')
#5 /usr/share/php/Icinga/Application/ClassLoader.php(301): require('/usr/share/php/...')
#6 [internal function]: Icinga\Application\ClassLoader->loadClass('Icinga\\Web\\Requ...')
#7 /usr/share/php/Icinga/Application/EmbeddedWeb.php(82): spl_autoload_call('Icinga\\Web\\Requ...')
#8 /usr/ in <b>/usr/share/php/Icinga/Application/ClassLoader.php</b> on line <b>276</b><br />
<br />
<b>Fatal error</b>: Icinga\Application\ClassLoader::requireZendAutoloader(): Failed opening required 'Zend/Loader/Autoloader.php' (include_path='/usr/share/icingaweb2/library/vendor:.:/usr/share/php') in <b>/usr/share/php/Icinga/Application/ClassLoader.php</b> on line <b>276</b><br />

The error is reproducible on all servers that I've tried so far (installed from scratch or updated from 14.04 LTS to 16.04 LTS).

When I manually add "/usr/share/php/libzend-framework-php" to the "include_path" I can get rid of the error but then I'm stuck with the error described in https://bugs.launchpad.net/ubuntu/+source/icingaweb2/+bug/1571402