Topic Last Modified: 2009-01-21

The Microsoft Exchange Server Best Practices Analyzer Tool parses the Web.config file to determine whether the file contains duplicate httpRuntime entries.

If the Analyzer locates duplicate httpRuntime entries, the tool generates a warning message.

Exchange Server 2007 uses the /owa virtual directory in Internet Information Services (IIS) to provide Web-based access to Exchange 2007 mailboxes. Outlook Web Access users can access their mailboxes from the local network or over the Internet.

Outlook Web Access is an ASP.NET-based Web application. The Web.config file is the main configuration file for ASP.NET applications. Web.config is an XML file that defines the configuration settings for ASP.NET applications.

Duplicate httpRuntime entries in the Web.config file may cause Outlook Web Access application pools in IIS to crash. To address this error, remove the duplicate entries from the Web.config file.

To modify the Web.config file
  1. On the Exchange 2007 server that hosts the /owa virtual directory, start Windows Explorer, and then open the Exchange Owa folder. By default, this folder has the following path:

    C:\Program Files\Microsoft\Exchange Server\ClientAccess\Owa

  2. Use a text editor, such as Notepad, to open the Web.config file.

  3. Remove any duplicate httpRuntime entries. In Exchange 2007, the default httpRuntime entry appears as follows:

    <httpRuntime maxRequestLength="30000" />

  4. Save the changes to the file, and then run the iisreset command to reset IIS.

Certain tools that are used to migrate information to Exchange 2007 or that provide interoperability between another messaging system and Exchange 2007 may require modifications to the Web.config file. In this scenario, we recommend that you do not create additional httpRuntime entries in the Web.config file. Instead, change the current httpRuntime entry in the Web.config file to address the requirements of the migration tool.