"HTTP 500 - Internal Server Error" error message when you use Outlook Web Access to access a front-end server

When you try to log on by means of Microsoft Outlook Web Access and access the Exchange virtual directory or public virtual directory, you receive the following error message:
When the Show Friendly HTTP error messages check box is not selected in the Internet Explorer advanced settings (On the Tools menu, click Internet Options, and then click the Advanced tab), you receive the following error message when you try to access the Exchange virtual directory or the public virtual directory:

Additionally, if you use the LDP tool to perform the following searches, you locate a public folder store or public folder stores in the Lost and Found Configuration container (LostandFoundConfig):

• Use the LDP tool to search the Configuration Container by using a filter of objectcategory=msExchPFTree (type the filter exactly as it appears). This LDAP search locates all of the public folder top-level hierarchies in the Exchange 2000 Server organization, for example:
  BaseDN = CN=Configuration, DC=domainname, DC=organization
  Filter= objectcategory=msExchPFTree
• Use the top-level hierarchy objects returned from the earlier query, use the LDP tool to expand down to each top-level hierarchy object and note the properties of each top-level hierarchy. After the properties have been returned on the top-level hierarchies, observe the value for the attribute msExchOwningPFTreeBL. The msExchOwningPFTreeBL attribute contains a listing of public folder stores that house the specific top-level hierarchies that you are viewing. Locate a public folder store that is in the Lost and Found Configuration container (part of the distinguished name indicates LostAndFoundConfig). For example, the distinguished name of a public folder store in the Lost and Found Configuration container appears similar to the following:
  CN=Public Folder Store,CN=First Storage Group,CN=InformationStore,CN=LostAndFoundConfig,CN=Configuration,DC=domain,DC=com

This problem may occur because front-end servers require information about all of the public folder top-level hierarchies in the Exchange 2000 Server organization. Front-end servers search for information about the top-level hierarchies, in the organization upon initialization, and then update cached information on these top-level hierarchies.

If any Public Folder Stores listed in the public folder hierarchy backlink attribute (msExchOwningPFTreeBL) are in the Lost and Found Configuration container (LostAndFoundConfig), the front-end server does not accept an Outlook Web Access client log on and returns the "HTTP 500" error message.

The front-end server requires knowledge of where every public folder store is located that is listed in the msExchOwningPFTreeBL attribute and if the front-end cannot to locate one of the stores, the front-end is prevented from finishing its top-level hierarchies discovery and does not service client logons.

This problem may also occur if Dsaccess cannot determine which Windows 2000 site it belongs to. DSaccess on a front-end server will not log an event ID, but if you try to start the System Attendant on that server you may receive the following event:

Event Type: Error
Event Source: MSExchangeSA
Event Category: General
Event ID: 1005
Date: date
Time: time
User: N/A
Computer: computer name
Description: Unexpected error No site name is available for this machine.
Facility: Win32 ID no: c007077f Microsoft Exchange System Attendant occurred. To resolve this issue make sure that your Windows 2000 Sites and Services are defined correctly.

This problem can have several causes, one of which is if an administrator adds an additional site but does not define subnets.

This problem may also occur if the back-end server is running a version of Microsoft Exchange Server 5.5 that is earlier than Service Pack 3 (SP3). Exchange Server 2003 requires that all back-end Exchange Server 5.5 computers run SP3 or a later version. Exchange Server 2003 reads the version number attribute on the server object to verify the service pack level of the Exchange Server 5.5 computer. If this version number attribute is less than SP3, attempts to log on to OWA will fail, and you will receive the error message that is described in the "Symptoms" section.

To resolve this problem, make sure that the public folder store that is located in the Lost and Found Configuration container is not valid, and then use LDP tool to remove the public folder store object from the Lost and Found Configuration container.

NOTE: The LDP tool is located in the Windows 2000 Support Tools. If this tool is not installed, you can install it from the Microsoft Windows 2000 CD-ROM. The file path is: WARNING: If you use the ADSI Edit snap-in, the LDP utility, or any other LDAP version 3 client, and you incorrectly modify the attributes of Active Directory objects, you can cause serious problems. These problems may require you to reinstall Microsoft Windows 2000 Server, Microsoft Exchange 2000 Server, or both. Microsoft cannot guarantee that problems that occur if you incorrectly modify Active Directory object attributes can be solved. Modify these attributes at your own risk.

To use the LDP tool to remove the objects, follow these steps:

1. Under Configuration Container, locate the LostAndFoundConfig container.
2. Expand the container, and then locate the public folder store that is listed in the previously mentioned msExchOwningPFTreeBL.
3. Right-click the public folder store object, click Delete, and then click OK.
   
   NOTE: Before you delete the object Microsoft recommends that you click New on the Connection menu. This procedure clears the screen so that you can copy and save the output in the right pane after the deletion.
   

Follow these steps for every public folder store object that was listed in the msExchOwningPFTreeBL attribute as being in the Lost and Found Configuration container. After Active Directory Replication occurs, Outlook Web Access clients can successfully connect to their front-end servers.

To resolve this problem when you have back-end Exchange Server 5.5 computers, install the latest service pack for Exchange Server 5.5 on the affected computer. After the version number attribute has replicated to Active Directory, OWA should function properly.

For more information about Exchange Server 5.5 service packs, see the following Microsoft Knowledge Base article:

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

Additionally, you can see the symptoms of this problem by means of a Network Monitor trace. After you use Network Monitor to obtain a network capture and you do not have filters set throughout the Outlook Web Access access and subsequent failure, the following information is seen when filtering the network capture after the fact:

1. Open the network capture and create a display filter.
2. Edit the Protocol expression to equal LDAP only.
3. To view the specific LDAP SearchRequest, add an expression by using the Property tab. Select LDAP Base Object, click Contains as the relation, click the ASCII button (defaults to hexadecimal), and type LostAndFoundConfig as the value.
4. Click OK, and then click OK again, to enable the display filter.
   
   NOTE: Observe an entry for a LDAP SearchRequest (or multiple entries) returning an LDAP base object that has the distinguished name of a public folder store that is in the Lost and Found Configuration container.

For additional information about the LDP tool, click the article numbers below to view the articles in the Microsoft Knowledge Base: For additional information about Network Monitor, click the article number below to view the article in the Microsoft Knowledge Base: