How Do I Solve This Please Help Me.

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Error:System.NullReferenceException: Object reference not set to an instance of an object. at Samregistration.Button1_Click(Object sender, EventArgs e)<br />

C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Security.Cryptography;
using System.Text;
using System.Configuration;
using System.Data;

public partial class Samregistration : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        try
{
       SqlConnection conn= new SqlConnection (ConfigurationManager.ConnectionStrings["Data Source=SUMIT92\\SQLEXPRESS;Initial Catalog=Registration1.dbo;Integrated Security=True;Connect Timeout=15;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False"].ConnectionString);
        conn.Open();
        string insertQuery ="insert into Regstration2 (UserName,E-mail,Password,Country) values (@Uname,@email,@password,@country)";
        SqlCommand com = new SqlCommand (insertQuery, conn);
        com.Parameters.AddWithValue("@Uname", TextBoxUN.Text);
            com.Parameters.AddWithValue("@email",TextBoxEM.Text);
            com.Parameters.AddWithValue("@password",TextBoxp.Text);
            com.Parameters.AddWithValue("@country",CN.SelectedItem.ToString());

            com.ExecuteNonQuery();
            Response.Write("Registration is sucessfull");

            conn.Close();
        }
        catch (Exception ex)
        {
          Response.Write("Error:"+ex.ToString());
        }
    }
}

Posted 6-Jul-15 19:41pm

Member 11818260

Updated 6-Jul-15 19:52pm

PIEBALDconsult

v2

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Comments

Harshad Kathiriya 7-Jul-15 1:51am

Do you debug the code? Find which object is not initialized.

PIEBALDconsult 7-Jul-15 1:53am

Luke... Use the debugger...
I would first check the value of CN.SelectedItem

harpreet.singh6771 7-Jul-15 2:11am

com.Parameters.AddWithValue("@country",CN.SelectedItem.Value.ToString());

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Fredrik Bornander · Answer 1 · 2015-07-06T20:11:00

It looks like you're trying to use the entire connection string as a key to a connection string. When you call the indexed on ConfigurationManager.ConnectionStrings I would expect that you're supposed to pass a name/key that identifies a connection string in the config, but you're passing the entire connection string as name/key.

Try changing

C#

SqlConnection conn= new SqlConnection (ConfigurationManager.ConnectionStrings["Data Source=SUMIT92\\SQLEXPRESS;Initial Catalog=Registration1.dbo;Integrated Security=True;Connect Timeout=15;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False"].ConnectionString);

to

C#

SqlConnection conn= new SqlConnection ("Data Source=SUMIT92\\SQLEXPRESS;Initial Catalog=Registration1.dbo;Integrated Security=True;Connect Timeout=15;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False"]);

Hope this helps,
Fredrik

OriginalGriff · Answer 2 · 2015-07-06T20:22:00

Best guess - no selected item in the combo box, so it fails on this line:

C#

com.Parameters.AddWithValue("@country",CN.SelectedItem.ToString());

Check your values at the top of the method and make sure that all the user inputs are valid before you even try to go to the database. For example: is the username entered? Is it unique? Is there an email, and is it a valid format?

In addition:
1) Your connection string name should not be the same as the connection string:

C#

SqlConnection conn= new SqlConnection (ConfigurationManager.ConnectionStrings["Data Source=SUMIT92\\SQLEXPRESS;Initial Catalog=Registration1.dbo;Integrated Security=True;Connect Timeout=15;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False"].ConnectionString);

Shoudl be somethign like:

C#

SqlConnection conn= new SqlConnection (ConfigurationManager.ConnectionStrings["Registration"].ConnectionString);

.
2) You should Dispose of Connection and Command objects - your code leaves the connection open if there is a problem because you don't close it in the catch block. Consider using a using block to ensure objects are always destroyed when you are finished with them:

C#

try
   {
   using (SqlConnection conn= new SqlConnection (ConfigurationManager.ConnectionStrings["Registration"].ConnectionString))
       {
       conn.Open();
       string insertQuery ="insert into Regstration2 (UserName,E-mail,Password,Country) values (@Uname,@email,@password,@country)";
       using (SqlCommand com = new SqlCommand (insertQuery, conn))
           {
           com.Parameters.AddWithValue("@Uname", TextBoxUN.Text);
           com.Parameters.AddWithValue("@email",TextBoxEM.Text);
           com.Parameters.AddWithValue("@password",TextBoxp.Text);
           com.Parameters.AddWithValue("@country",CN.SelectedItem.ToString());

           com.ExecuteNonQuery();
           Response.Write("Registration is sucessfull");
           }
       }
   }
   catch (Exception ex)
       {
       Response.Write("Error:"+ex.ToString());
       }

3) And please, never store passwords in clear text - it is a major security risk. There is some information on how to do it here: Password Storage: How to do it.[^]
Also see here: Code crime: Text based passwords[^]

How Do I Solve This Please Help Me.

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