FIX: Error message when you run a client application that is built on the .NET Framework 2.0: "The request was cancelled. An underlying connection that was expected to be open was closed"

A client application is built on the Microsoft .NET Framework 2.0. The HTTP Keep-Alives option is enabled on the Web server. When the application calls a Web service, you may receive the following error message:

This problem occurs because the Web server sends a TCP FIN request during a delay between Web services calls. This TCP FIN request indicates that the Keep-Alive connection timed out. However, the client application still uses the connection on the next request. Therefore, the TCP reset occurs on the Web server, and you receive the error message.

Hotfix information

A supported hotfix is now available from Microsoft. However, it is intended to correct only the problem that this article describes. Apply it only to systems that are experiencing this specific problem.

To resolve this problem, contact Microsoft Customer Support Services to obtain the hotfix. For a complete list of Microsoft Customer Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Prerequisites

You must have the .NET Framework 2.0 installed to apply this hotfix.

Restart requirement

You do not have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

The .NET Framework 2.0, x86-based version

The .NET Framework 2.0, x64-based version

The .NET Framework 2.0, Itanium architecture version

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

For more information about how to enable HTTP Keep-Alives in Internet Information Services (IIS) 6.0, visit the following Microsoft Web site: For more information, click the following article number to view the article in the Microsoft Knowledge Base: