Object reference not set to an instance of an object.

Ahmed Khalid

Hi,

I have implemented Session in Master Page and in Login Pages for User and Admin in my application. The application is working fine but it frequently prompts "Object reference not set to an instance of an object." during Login process and whenever the home page is being displayed or page gets refreshed and it stops at if (Session["role"].Equals("")) in debug mode

I tried to comment the if (Session["role"].Equals("")) and keep the if (Session["role"].Equals("user")) and if (Session["role"].Equals("admin")) un commented. But behaviour remains the same.

Any idear please?

4 Replies

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Pankajkumar Patel3y ago

Accepted answer

Hi Ahmed Khalid,

For your given code you can try as following:

protected void Page_Load(object sender, EventArgs e)
{
    string Status = "Hi";

    if (Session["role"] == null)
    {
        // set session
        Status = "null"; 
    }
    else
    {
        // do some thing here
        if (Session["role"].Equals("user"))
        {
            Status = "user";
        }
        else if (Session["role"].Equals("Admin"))
        {
            Status = "Admin";
        }
    }

    Response.Write(Status);
}

For more details:

How to check if session is null or not in C#
- https://social.msdn.microsoft.com/forums/en-US/5d65f9d2-c0fa-4b23-8b9e-203d02baf233/how-to-check-if-session-is-null-or-not-in-c?forum=aspgettingstarted

Hope this will help you!

Ahmed Khalid3y ago
Thanks Patel. The code has worked. No more error messages
Ahmed Khalid3y ago
Hi Patel,

i have checked but it returns the same error. Kindly find the full code below:

protected void Page_Load(object sender, EventArgs e)
{


try
{

//if (Session["role"] != null && Session["role"].Equals("user")) //suggested code
if (Session["role"].Equals("")) //old code
{
Btn_Login.Visible = true; // user login link button

Btn_MyProfile.Visible = false; // sign up link button
Btn_Logout.Visible = false; // logout link button
Btn_HelloUser.Visible = false; // hello user link button

Btn_AdminLogin.Visible = true; // admin login link button
Btn_ManageParents.Visible = false; // author management link button
Btn_ManageUsers.Visible = false; // publisher management link button
}
if (Session["role"].Equals("user"))

{
Btn_Login.Visible = false; // user login link button

Btn_MyProfile.Visible = false; // sign up link button
Btn_Logout.Visible = true; // logout link button
Btn_HelloUser.Visible = true; // hello user link button
Btn_HelloUser.Text = "Hello " + Session["FullName"].ToString(); // display hello user string

Btn_AdminLogin.Visible = true; // admin login link button
Btn_ManageParents.Visible = false; // author management link button
Btn_ManageUsers.Visible = false; // publisher management link button
}
else if (Session["role"].Equals("Admin"))
{
Btn_Login.Visible = false; // user login link button

Btn_MyProfile.Visible = false; // sign up link button
Btn_Logout.Visible = true; // logout link button
Btn_HelloUser.Visible = true; // hello user link button
Btn_HelloUser.Text = "Hello Admin"; // display hello Admin string

Btn_AdminLogin.Visible = false; // admin login link button
Btn_ManageParents.Visible = true; // author management link button
Btn_ManageUsers.Visible = true; // publisher management link button
}
}
catch (Exception ex)
{
Response.Write("");
}
}

And in Login Pages for Admin and User, i have implemented below code on Login Button click:

protected void btn_Login_Click1(object sender, EventArgs e)
{
try
{
SqlConnection con = new SqlConnection(strcon);
if (con.State == System.Data.ConnectionState.Closed)
{
con.Open();
}
SqlCommand cmd = new SqlCommand("Select * from [Admin_Tbl] " +
"where [UserName] = '" + txt_userName.Text.Trim() + "' and " +
"[Password] = '" + txt_Password.Text.Trim() + "' and [Status] = 'Active'", con);

SqlDataReader dr = cmd.ExecuteReader();
if (dr.HasRows)
{
while (dr.Read())
{
//Response.Write("");
// Session["role"] = "user"; // for User Login Page

Session["role"] = "Admin"; // for Admin Login Page
Session["FullName"] = dr.GetValue(1).ToString();
Session["LoginName"] = dr.GetValue(2).ToString();
Session["UserType"] = dr.GetValue(5).ToString();

//Session["UserStatus"] = dr.GetValue(11).ToString();
}
Response.Redirect("homepage.aspx");
}
else
{

Response.Write("");
}

}
catch (Exception ex)
{
Response.Write("");
}

}
Pankajkumar Patel3y ago
Hi Ahmed Khalid,

First check not equal to null and than equals as like following:
```
if (Session["role"] != null && Session["role"].Equals("user")
```
Hope this will help you!