This post originated from an RSS feed registered with .NET Buzz by Peter van Ooijen. Original Post: Scripting errors on an aspx page, validatorcontrols and causesvalidation ('undefined' is null or... Feed Title: Peter's Gekko Feed URL: /error.htm?aspxerrorpath=/blogs/peter.van.ooijen/rss.aspx Feed Description: My weblog cotains tips tricks and opinions on ASP.NET, tablet PC's and tech in general. Latest .NET Buzz Posts Latest .NET Buzz Posts by Peter van Ooijen Latest Posts From Peter's Gekko

The ASP.NET toolbox has some nice validator controls like RequiredFieldValidator and RangeValidator. These perform a first validation of client input in the browser. On postback the validation is repeated on the server. The client side validation is not supported in every browser and is skipped in some scenarios. A side effect of the validation scripts is that a page with validator controls sometimes pops up quite mysterious scripting errors. This is because validation is, by default, performed on every roundtrip. In some scenarios this can lead to invisible controls being validated with null values and script errors like 'undefined' is null or not an object.

The good thing is that you can disable validation on a control base. Every control which can force a postback, like a button or linkbutton, has the CausesValidation property. Default it is set to true. Set it to false in case there is nothing to validate and your script errors are gone.