How to Fix 'Object reference not set to an instance of an object' Error When Retrieving Connection Strings from App.config?

Accessing Connection Strings in App.config

Your code is trying to read a connection string from your application's App.config file using the ConfigurationManager class, but a NullReferenceException is occurring because the object reference isn't properly initialized.

Here's a streamlined solution:

string connectionString = System.Configuration.ConfigurationManager.ConnectionStrings["Test"].ConnectionString;

This concise code directly accesses the ConnectionStrings collection within the ConfigurationManager and retrieves the connection string using its name ("Test" in this example).

Before running this, verify that:

1. Your project includes a reference to System.Configuration.dll. This is usually included by default in .NET Framework projects, but may need to be added manually in some .NET Core or .NET projects.
2. The connection string named "Test" actually exists within your App.config file with the correct syntax. A typical entry looks like this:

<configuration>
  <connectionStrings>
    <add name="Test" connectionString="your_connection_string_here" providerName="System.Data.SqlClient" />
  </connectionStrings>
</configuration>

Remember to replace "your_connection_string_here" with your actual connection string. This corrected approach should eliminate the NullReferenceException and allow successful retrieval of your connection string.

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