The underlying connection was closed: A connection that was expected to be kept alive was closed by the server. (.NET)

Error Message

When running applications on .NET with Address Finder and Map Image services, the following error is displayed:

"The underlying connection was closed: A connection that was expected to be kept alive was closed by the server."

After the error, the application continues to run; the next message to the server is fine.
The error occurs after services have run a while and sometimes at the start of the application after it was run previously.

Cause

The Authentication method getToken is throwing the exception due to a problem with an HTTP proxy server that exists between the Web service and the .NET client.

Solution or Workaround

Enter the proper proxy configuration settings into the .NET client.
See the link to a Microsoft white paper in the Related Information section below for more information and solutions for this problem.

There is also another property, KeepAlive, which can fix this.

Code:
webRequest.KeepAlive = false;

See the link for an Alternate solution in the Related Information section below for more information.