Browser version numbers continue to march on. IE9 is here, IE10 is coming, Firefox 5 and 6 are here with 7 and 8 in the wings, Opera's on 11, and Chrome is on, I dunno, somewhere between 14 and 50. Regardless, we'll all be on version 99 before The Singularity.
There are two ways to fix this: one is a machine-wide fix, the other is a way to fix individual sites.
We're releasing a hotfix that will fix these, which you'll be able to get to via some KB articles. These KBs with fixes are live and are the best way to update your system. The fixes solve the browser-detection issue forever for all sites on a machine. These will be rolled up into future versions of the framework and will eventually also be on Windows Update.
What the fixes do is update the ie.browser and firefox.browser files in \Windows\Microsoft.NET\Framework\<version>\Config\Browsers with new and future-proofed versions of these browser definitions. Nothing else is affected.
If you don't have access to the whole machine and/or just want to update a single project, use NuGet to install the App_BrowsersUpdate package. Your site structure in Solution Explorer will then look like the image at right. Note that NuGet uses .NET 4, so for systems that have only .NET 2, you'll need to get the ZIP file and put the new browser files in App_Browsers manually.
Updating the whole machine is the preferred way to fix this.
If you're interested in more detail than you need, I’ve uploaded the updated versions of firefox.browser and ie.browser files that are expected to ship with the next version of ASP.NET. The files and source is up at my BitBucket repo if you are interested in the details.
Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. I am a failed stand-up comic, a cornrower, and a book author.
Disclaimer: The opinions expressed herein are my own personal opinions and do not represent my employer's view in any way.