"Page.IsValid cannot be called" occurs in Page_PreRender event handler

Question

Hi, I'm currently learning ASP.NET, and read that the page validation occurs after Page.Load(). When I put if (Page.IsValid == true) whatever;

then I get an error, even though that line is in my Page_PreRender() event handler.

How does that make sense?

Thanks in advance, just trying to understand it fully.

Answer 1

You either have to have a control that causes validation doing the postback (CausesValidation="true") or actually call Page.Validate() manually for Page.IsValid to be accessible...otherwise validation hasn't happened, so there's just nothing to check, the value would be meaningless, which is the current error you're seeing.