Whilst testing an existing page we had developed, i came across this error message.
Unable to get property 'call' of undefined or null reference
This occurred on one of our MVC pages that use the telerik grid controls for MVC.
I used F12 debugger or Firebug to check the network activity and the files downloaded.
I found jquery.validate.min.js was being attached twice.
One was a straight forward script that was being bundled with the site.
The other instance was added by the Telerik ScriptRegistrar.
To prevent this second copy being used , i changed the line of code for the script registrar as follows:
Html.Telerik().ScriptRegistrar().Globalization(true).jQuery(false).CombinedComponentFile(true))
to
Html.Telerik().ScriptRegistrar().Globalization(true).jQueryValidation(false).jQuery(false).CombinedComponentFile(true))