There is a problem with installing Piwik when
mbstring.func_overload in php.ini is not
Piwik just throws exception like
Can't install Piwik: An exception has been thrown during the rendering of a template ("parse error: failed at content: ; line: 3682"winking smiley in "<a class='mention' href='https://github.com/Installation'>@Installation</a>/layout.twig" at line 40.. And it's not so easy to understand what is wrong.
It's kind of popular issue:
:+1: for the record the installation doesn't even work if that setting is on