I want to connect to sql DB, and I have in my Sharepoint project an App.config (with properties : Build "None", Copy to Output directory"Copy always"), I added a reference to System.Configuration.dll (Version 2), and my app.config is like that :

    <add name="ExchangeRate" connectionString="Data Source=CH-SQL;Initial Catalog=COMMON;User ID=_cb;Password=***" />

I call the connection string in my code :

using System;
using System.Configuration;
 exchangeRate = System.Configuration.ConfigurationManager.ConnectionStrings["ExchangeRate"].ConnectionString;

in my project.exe.config , I can see connectionString

I have the following error :

Object reference not set to an instance of an object

Maybe my app.config is not working correctly

Help please


1 Answer 1


This is how you define your connection in web.config

      <add name="MyConnectionString" 
         connectionString ="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\PUBS.MDF; 
                            Integrated Security=True;User Instance=True" />

And to use the connection string, use the below code.

private SqlConnection con = null;
con = new SqlConnection(ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString);
  • I tried your solution but it still same error , PS : when I use a string instead of connectionString it connects me
    – BKChedlia
    Commented Aug 17, 2016 at 9:45
  • Are you able to connect with DB now ?
    – Muskan
    Commented Aug 17, 2016 at 9:53
  • When I put string (and not read from app.config) I am able : string connstr = "Data Source=CH-SQLD;Initial Catalog=LOGS;User ID=***;Password=***"; DataProviderUtility.ExecuteStoredProcedureToSqlDatabase(sqlParam, StoredProcedures.CREATELOG, connstr)
    – BKChedlia
    Commented Aug 17, 2016 at 9:55
  • 1
    Have you added this connection string in STS and Central admin web.config file as well, if not pls try that
    – Muskan
    Commented Aug 17, 2016 at 10:00
  • could you please give me further details, sorry for the dumb questions : what's STS? I cannot find web.config (it's a solution developed by another person, I am just making few changes)
    – BKChedlia
    Commented Aug 17, 2016 at 10:04

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