OKB-124: Refreshing a feed results in a message saying that "The underlying connection was closed: The server committed an HTTP protocol violation"

In .NET Framework 1.1 Service Pack 1, Microsoft locked down the logic in their HTTP protocol API's to prevent possible security holes. With this change, .NET applications will now throw an HTTP protocol violation if the server responds with any HTTP headers that Microsoft considers invalid. It is likely that if you get this error, it is because the server is sending back a header named 'Last Modified' instead of the standard header named 'last-modified'.

There are two solutions to this problem:

Correct the blog itself

Contact the owner of the blog and encourage them to correct the header. We have found that blogs created using WordPress version 1.2.2 or older exhibit this problem, so upgrading to the latest version of WordPress should remedy the problem for the blog.

Instruct .NET to ignore unsafe headers

If you would like to disable unsafe header detection:

1. Create a file named iexplore.config in the same directory as your iexplore.exe (usually C:\Program Files\Internet Explorer)
2. Place the following XML in the file that you have just created

<configuration>
<system.net>
<settings>
<httpWebRequest useUnsafeHeaderParsing="true"/>
</settings>
</system.net>
</configuration>

3. Create a file named onffeeds.config in your Onfolio install directory
4. Place the same XML in this file
5. If you use the Onfolio Deskbar, you will need to create a onfdesk.config file containing the same XML in your Onfolio install directory
6. If you use Onfolio in Firefox, you will need to create a firefox.config file containing the same XML in the Firefox install directory

You can see more information about this in Microsoft's Knowledge Base