JavaScript errors in IE10 and the site is working fine in the rest browsers.

[Telerik Admin]

Hello Community,

Recently lots of the developers reported that their sites are not working in IE10. Depending on what controls they have on the page, the errors can be:

• "Unable to get property 'PageRequestManager' of undefined or null reference"
• "__doPostBack" is undefined or not an object.

• "'$get' is undefined"

If you have some of these errors only on IE10, and your site is working in other browser, it is most probably that the MicrosoftAjaxWebForms.js fails to be included in the scripts for your page. This is known to be caused by bug in the browser definition files in .NET 4.0 and .NET 2.0 used by the ASP.NET.

Since the RadControls are made on top of the AjaxWebForms,if the Microsoft's scripts are not loaded properly, the RadControls will not work as well. For example if you have RadAjaxManager in your page, it's initialization will fail, when PageRequestManager is requested, you might think at first that the problem is in the RadAjaxManager, but on later look you see that the PageRequestManager is defined inside the MicrosoftAjaxWebForms.js where is the actual problem.

You have several options to confirm that this is the issue:

• Open the developer tools of IE10, capture the network traffic and see if the bot Microsoft scripts (MicrosoftAjax and MicrosoftAjaxWebForms) are included.
• Run the sample web page attached to this post, click the "TestPostBack", if you get JavaScript error then the MicrosoftAjaxWebForms is not loaded properly.
• Run your site in other browsers like IE9, Firefox, Chrome, Opera. If it works on all of them and not on IE10, then the problem is the definition files.

Luckily there is solution for the problem: .NET fix for your server released by Microsoft.
For .NET 4.0 check this one: http://support.microsoft.com/kb/2600088
For .NET 2.0:
http://support.microsoft.com/kb/2600100 for Win7 SP1/Windows Server 2008 R2 SP1, Windows Vista/Server 2008, Windows XP/Server 2003
http://support.microsoft.com/kb/2608565 for Win7/Windows Server 2008 R2 RTM

Since the problem is not particularity in the RadControls, you might find usable information out in the web, see this blog post by Scott Hanselman for more information:
Bug and Fix: ASP.NET fails to detect IE10 causing _doPostBack is undefined JavaScript error or maintain FF5 scrollbar position

All the best,
Vasil,
the Telerik team