The type initializer for 'MyClass' threw an exception

Question

Check the InnerException property of the TypeInitializationException; it is likely to contain information about the underlying problem, and exactly where it occurred.

This problem can be caused if a class tries to get value of a key in web.config or app.config which is not present there.

e.g.
The class has a static variable

private static string ClientID = System.Configuration.ConfigurationSettings.AppSettings["GoogleCalendarApplicationClientID"].ToString();

But the web.config doesn't contain the GoogleCalendarApplicationClientID key

The error will be thrown on any static function call or any class instance creation

The type initializer for 'CSMessageUtility.CSDetails' threw an exception. means that the static constructor on that class threw an Exception - so you need to look either in the static constructor of the CSDetails class, or in the initialisation of any static members of that class.

I ran into the same problem, when I was using a static methods in a Util class, just like you had used CSMessageUtility.CSDetails.

The problem was that during the static initialization of the class (using the static constructor), the framework also initialize the the static variables (fields) in the class. I had a static variable that attempts to read values from app.config, and app.config was missing the respective settings, thus resulting in an un-handled exception. This resulted in getting the

"Object reference not set to an instance of an object."

as the inner exception.

One other thing to check when these initialize errors are thrown would be to check if the target .NET version is installed on the server. You can right click the project and see what .NET version the application is targeting.

This can happen if you have a dependency property that is registered to the wrong owner type (ownerType argument).

Notice SomeOtherControl should have been YourControl.

public partial class YourControl
{
    public bool Enabled
    {
        get { return (bool)GetValue(EnabledProperty);   }
        set { SetValue(EnabledProperty, value); }
    }
    public static readonly DependencyProperty EnabledProperty =
        DependencyProperty.Register(nameof(Enabled), typeof(bool), typeof(SomeOtherControl), new PropertyMetadata(false));
}

I've had the same problem caused by having two of the same configuration properties (which matches the app.config):

[ConfigurationProperty("TransferTimeValidity")]