Object reference not set to an instance of an object for SqlConnection

Question

I got this error Object reference not set to an instance of an object. I can't find what is the problem. Thanks

protected void Check_Clicked(Object sender, EventArgs e)
{

    SqlConnection con = new SqlConnection(System.Configuration.ConfigurationManager.
                            ConnectionStrings["DbCar"].ConnectionString);
 .....
}

 <connectionStrings>
   <add name="ConnectionString" connectionString="Data  
    Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\DbCar.mdf;Integrated 
    Security=True;User 
    Instance=True" providerName="System.Data.SqlClient"/>
 </connectionStrings>

Almost all cases of `NullReferenceException` are the same. Please see "[What is a NullReferenceException in .NET?](http://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-in-net)" for some hints. — John Saunders, Jan 13 '14 at 15:14

score 2 · Accepted Answer · answered Jan 13 '14 at 15:13

2

Your connection string name ConnectionString not DbCar

new SqlConnection(System.Configuration.ConfigurationManager.
                        ConnectionStrings["ConnectionString"].ConnectionString);

answered Jan 13 '14 at 15:13

Selman Genç

100,147
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score 1 · Answer 2 · answered Jan 13 '14 at 15:14

1

The name of the connectionstring is ConnectionString rather than DbCar

SqlConnection con = new SqlConnection(System.Configuration.ConfigurationManager.
                        ConnectionStrings["ConnectionString"].ConnectionString);

answered Jan 13 '14 at 15:14

Shai

25,159
9
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score 1 · Answer 3 · answered Jan 13 '14 at 15:15

1

ConnectionStrings["DbCar"]

You do not have a connection string by that name. You need to rename your connection string from ConnectionString to DbCar or change the name in the code to ConnectionString.

answered Jan 13 '14 at 15:15

Neil Kistner

11,623
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Sudhakar Tillapudi · Answer 4 · 2014-01-13T15:20:04.473

Problem : You are refering to invalid connectionstring name. there is no ConnectionString in your configuration file with name DbCar.

Solution : you need to refer to the valid ConnectionString Name from the configuration file.

Solution 1: either change the name of DbCar to ConnectionString from the code.

SqlConnection con = new SqlConnection(System.Configuration.ConfigurationManager.
                            ConnectionStrings["ConnectionString"].ConnectionString);

Solution 2: or change the name of the connectionstring in config file from ConnectionString to DbCar.

<connectionStrings>
   <add name="DbCar" connectionString="Data  
    Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\DbCar.mdf;Integrated 
    Security=True;User 
    Instance=True" providerName="System.Data.SqlClient"/>
 </connectionStrings>

Object reference not set to an instance of an object for SqlConnection

4 Answers4