Sys.ArgumentUndefinedException
Raised by the Microsoft AJAX Library framework when an argument for a required method parameter is undefined.
Remarks
When a function or method is called in client script and an argument for a required parameter is undefined, a Sys.ArgumentUndefinedException object is created by using the Error.argumentUndefined function.
For more information about how to raise this error, see Error.argumentUndefined Function.
For more information about how to handle error conditions, see Debugging and Tracing AJAX Applications Overview.