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On Firefox 3.6.x on Mac and Windows, Google Analytics tracking code leads to an Error 400 page


Our business sent out an email campaign that has several links containing Google Analytics tracking code in the URL.

In the tracking code, which is automatically generated via the email campaign software, is an em-dash. The URLs works in every browser (Google Chrome, Safari, Windows) and in older versions of FireFox. They do not work in 3.6.x versions of FireFox in both Mac and Windows.

As a result, when customers click on a link in the email, they get a page that says "HTTP Error 400 - request is badly formed" because FireFox interprets the em-dash as garbage.

Once this error occurs none of the pages in the site can be accessed unless a specific cookie is removed.

Seeing how many people do not know how to clear cookies - it is especially cryptic in the Windows version of FF 3.6.10 - what are the chances that there will be a release of Firefox to remedy this problem? And is there anything else that could be done?

Additional System Details

Sites Affected


Installed Plug-ins

  • getplusplusadobe16291
  • Default Plug-in
  • Shockwave Flash 10.1 r85
  • Google Update
  • Windows Presentation Foundation (WPF) plug-in for Mozilla browsers
  • Npdsplay dll
  • DRM Store Netscape Plugin
  • DRM Netscape Network Object


  • User Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv: Gecko/20100914 Firefox/3.6.10

More Information

tmiranda 0 solutions 1 answers

Weird. We are having this same problem as well. Ours happens in Chrome as well. What I have figured out is -at least for us - is its somethign to do with the Google Analytics tracking cookie on our site. If I go to cookies and then delete the _umtz cookie, the site will load fine. In the time being I have set "pageTracker._setCampaignTrack(false); " in our tracking code to keep the script from dropping the cookie in users browsers.

CG-2800 0 solutions 2 answers

We are experiencing this very same issue, however we have discovered that it extends beyond Google Analytics. We use some other tracking software as well which is causing an error. Also, if you are using an email service provider, some of their code will be included in eblast campaigns.

Why is it that Mozilla is blocking some of the tracking codes?