Question

I am building a C# application, and a problem occurred, I have no idea how to fix it though.

I have a couple of forms, and now I want to add a form which is inherited by another. When I want to view the [Design] screen of the new form, it gives me the following error:

Object reference not set to an instance of an object.

Now I found out that the problem was the connection string, which is located in the app.config file:

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

This is my code for the connectionString in C#:

string connectionString = ConfigurationManager.ConnectionStrings["ConnString"].ConnectionString;

If I use the string like the one above, I get the Object Reference blabla error. Suprisingly, when I use the following code, the form just works perfectly fine:

string connectionString = "Data Source=.\\SQLEXPRESS;Initial Catalog=PVB;Integrated Security=True";

Does anyone have a clue how I can fix this problem? Yes, I’ve added the System.Configuration reference to the solution, so that’s not the problem, I guess..

Answer 1

Please review the following URL which might resolve your issue. It seems that the problem here is simulair:

access app.config from inherited form