I am getting this error very ofter.
Error in Piwik (tracker): Invalid idSite: '0', referer: http://www.example.com/my-page.html
I have site with about 100.000 pageviews per week and this error happens ones every 10-15 second in the apache log.
It definitely comes from core/Tracker/Request.php
Is there any solution for this? I believe its a bug because I have only 1 site with PIWIK tracking code installed and about half of traffic actually makes on the PIWIK end.
Maybe the tracking code is not integrated correctly at some point. Would you mind sharing the site you are tracking. I would have a short look if everything is correct...