[rani_240887]

hi this is rani
i m getting dis error (system.nullreferenceexception object reference not set to an instance of an object. c sharp)which i am not able to solve it.here is my code:

DataSet ds = new DataSet();

// error occurs here
us.Username = this.Session["UserId"].ToString();

ds=us.get_id(us.Username);
us.Username = txtsubscription.Text;
us.get_id(us.Username);
string lm = ds.Tables[0].Rows[0]["UserId"].ToString();

i have created class file also but getting error ovr here

[Nakor]

There's not enough code there to really tell what's going on. Are you sure that Session["UserId"] has a value? Where is the "us" object created at?

If you step through this with the debugger it should be pretty easy to see which object is null here.

[eclipsed4utoo]

ToString will throw a NullReferenceException if it's called on a null object.

If the session variable doesn't exist, the Session will return null.

Therefore, your session variable UserId is either does not exist in the session, or it's value is null.

[Nakor]

Whatever "us" is could also be null