connectionstring: object reference not set to an object instance

Question

I want to connect with a db with a connectionstring in an application config file but always get this error :

object reference not set to an object instance

In the first code line with the ConfigurationManger I have checked it several times but I do not think that I have made a mistake. Hope you can find something.

Code

string con = ConfigurationManager.ConnectionStrings["dbConnect"].ConnectionString;
            using (SqlConnection conn = new SqlConnection(con))
            {
                SqlDataAdapter adapter = new SqlDataAdapter("Select* From dsds m with (nolock) inner join asdas a with (nolock) on a.id = m.id where  test....., conn);
                ds = new DataTable(" ");
                adapter.Fill(ds);
                dataGridView1.DataSource = ds;

App.config

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<connectionStrings>
<add name="dbConnect"
     connectionString="Data Source=test;Initial Catalog=as;Integrated Security=True"
     providerName="System.Data.SqlClient" />
</connectionStrings>
</configuration>

Possible duplicate of [What does "Object reference not set to an instance of an object" mean?](http://stackoverflow.com/questions/779091/what-does-object-reference-not-set-to-an-instance-of-an-object-mean) — ViRuSTriNiTy, Aug 23 '16 at 10:11

score 2 · Accepted Answer · edited May 23 '17 at 11:55

2

string con = System.Configuration.ConfigurationManager.ConnectionStrings["dbConnect"].ConnectionString;

Edit:

As you have two app.config, you can either delete one, or if you want to control programatically which app.config to use, Refer How can I use several Application Configuration Files in one project?

edited May 23 '17 at 11:55

Community

1
1

answered Aug 23 '16 at 10:31

Richa Garg

1,888
12
23

Have you referenced the System.Configuration dll in your project? – Richa Garg Aug 23 '16 at 10:39
Do you have multiple app.config files? – Richa Garg Aug 23 '16 at 10:41
yes i have otherwise i would not have get this error – myworld Aug 23 '16 at 10:42
Sorry. I could not get for which question it was Yes. – Richa Garg Aug 23 '16 at 10:43
Can you please verify if System.Configuration is present in the References folder of your project? – Richa Garg Aug 23 '16 at 10:47
Does both the app config files contain the connection string? – Richa Garg Aug 23 '16 at 10:50

connectionstring: object reference not set to an object instance

1 Answers1