Piwik 3.0.2 issue

/var/www/html/piwik/plugins/RssWidget/RssRenderer.php(47): Warning - simplexml_load_string(): s = s.replace(/</g, "<").replace(/>/g, ">"); - Piwik 3.0.2

The RssWidget, which shows the latest piwik news needs the php xml module to parse the RSS feed.

So you can either disable the plugin (and don’t see the piwik news as a widget) or check if you have the correct module installed (e.g. php7.0-xml in debian)