Some time ago Microsoft released Internet Explorer 11 and some of the users of a web applications I am working on, reported that they were not able to use the web application, they clicked some buttons and nothing happend.

After installing IE11 I was able to reproduce the issue and find root cause: asp.net was not generating the Javascript files required by the webforms controls. These strange behaviour was caused because asp.net did’t recognize the web browser that was sending the request (IE11).

This problem with a recommended solution is explained here by Mr. Hanselman.

In our case we just added a browser definition file to fix the problem. We know this is not the better solution, but we are about migrating to ASp.NET 4.5 that has a built-in fix for this  issue.

It is incredible that the same issue happened when IE10 was released.