session returns null object in asp.net

Question

I am developing asp.net web application in which i am using Session to store user related data.Though i am storing data in session object when i am trying to retrieve it gives me error :

Object reference not set to an instance of an object.

Setting session variable

somewhere in code behind of aspx page (myfile.aspx.cs)

HttpContext.Current.Session["ProjectID"] = Request.QueryString["Pid"].ToString();

Retrieving Session Variable

Normal Business Logic C# Class (Someclass.cs)

sProjectID = HttpContext.Current.Session["ProjectID"].ToString();

It gives me error on above line. It looks weird to me. can anyone explain this ?

Edit:

Call to class pass through generic handler (.ashx) page

Solution

If it is really the line of code you showed, that produces exception, it means your "Normal Business Logic" is running in a non-HttpRequest handling thread, where thing such as Context and Session are not available. Check that HttpContext.Current and HttpContext.Current.Session are not null.

Update:

After seeing your edit - to have access to Session, your handler must include IRequiresSessionState in its class declaration. See: HttpContext.Current.Session is null in Ashx file.

Comments

[Rajeev Kumar]

You should put it as comment. This is not an answer

[Shaggy]

@Shark i did that. value goes in session varable

[zblago]

Is your business logic in separate assembly (project inside Visual Studio Solution). If it try to get a value from the session and pass like method parameter. Also, check answer from modiX.