Adblock Plus does have a filter to block various analytics. If Adblock Plus and/or the filter is causing the Javascript errors, then you should be reporting it to the respective developers.

Otherwise, the javascript error implies the analytics code wasn’t added correctly to the web page. If you can provide an external URL to your site, we can take a look.

Replying to [vipsoft](comment:1):

> If you can provide an external URL to your site, we can take a look.

Just navigate to http://piwik.org/ and have a look at the error console. German output (Error/Source/Line):

Fehler: piwik_log is not defined
Quelldatei: http://piwik.org/
Zeile: 293

As said in my post piwik.js is blocked by adblock which disables all functions including piwik_log(). No error message is presented to the user. it’s just an entry in the JS error log. My problem is that no visitor data is logged by piwik.

I spent some time wondering why all hits from other browsers than Firefox 3 were correctly logged and tracing it back to adblock plus. It’s not a piwik bug, but I didn’t find any explanation for it an thought it useful to document it for users having the same problem.

As you say, this is not a Piwik bug. closing