how to solve error for connection string in mvc?

Anjali Khan

9y4.5k.NET

hi frnds

my connection string is

string constr = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;

and in web.config

but i am getting the error like

Object reference not set to an instance of an object.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:

Line 39:
{ Line 40: List items = new List();
Line 41: string constr = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
Line 42:
Line 43: using (SqlConnection con = new SqlConnection(constr))

5 Replies

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Ramesh Palanivel9y ago
Accepted answer
Hi Anjali,

Try this connection string, I think u missed provider
<add name="ConnectionString" connectionString="Server=Sever-2019; Database=Customer ; Integrated Security=True";providerName="System.Data.SqlClient" />
+2
Jitendra Shekhawat9y ago
Add the following connection string to the element in the Web.config file.1
XML

connectionString="Data Source=(LocalDB)\v11.0;AttachDbFilename=|DataDirectory|\Movies.mdf;Integrated Security=True"
providerName="System.Data.SqlClient" />

The following example shows a portion of the Web.config file with the new connection string added:
XML

+1

Jitendra Shekhawat9y ago

 name="ConnectionStringName" providerName="System.Data.SqlClient"

connectionString="Data Source=190.190.200.100,1433;Initial Catalog=MyDatabaseName;

Integrated Security=False; User ID=MyUserID;Password=MyPassword;

 MultipleActiveResultSets=True" />

Ravi Patel9y ago
Hi ,

if sql server install in local system then

for example

for more details check this

http://csharp.net-informations.com/data-providers/csharp-sql-server-connection.htm
+1
Manas Mohapatra9y ago
Mostly ConfigurationManager.ConnectionStrings["ConnectionString"] returns null, so you are getting null exception.

To investigate the issue, first check how many connection strings.
ConfigurationManager.ConnectionStrings.Count

ConfigurationManager.ConnectionStrings[] ; // It takes either index as integer or connection string name.

Secondly use index like: ConfigurationManager.ConnectionStrings[0].ConnectionString;
Thirdly make sure that in connectionstring is present in correct web.config file of root directory.
+1