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Message Queuing messages may be silently discarded by the receiver. The problem occurs when the messages are sent by using the HTTP protocol and if the messages are sent through a Microsoft Internet Security and Acceleration (ISA) Server.
You can find the following entry in the Internet Information Services (IIS) log files:
A problem in ISA Server 2004 may cause the receiver of a Message Queuing HTTP message to receive the POST command without the letter P. This command now reads as an "OST" command. Therefore, the receiver returns error 501 that means "not implemented" and then discards the message.The default handling of error 501 was changed from drop to retry. Therefore, the HTTP message that hits the ISA problem is re-sent. The second message is always successful because the ISA bug occurs only when two subsequent POST requests are sent without waiting for a reply in the middle.
Service pack information
To resolve this problem, obtain the latest service pack for Microsoft Windows XP. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
322389 How to obtain the latest Windows XP service pack
A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.
If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.
Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site:
Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.
No prerequisites are required.
You must restart your computer after you apply this hotfix.
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