XADM: Backout of Upgrade Causes Replication to Fail (195908)

SYMPTOMS

If it has been necessary to restore a server computer running Exchange Server 4.0 after a failed attempt to upgrade to Exchange Server 5.5, you may experience directory replication failures between sites, including the folowing events -

   Event ID 1091 Source:MSExchangeDS Category:Replication

   The directory replication agent (DRA) couldn't connect to the MTA with
   name
   /o=Microsoft/ou=BACKOUT/cn=Configuration/cn=Servers/cn=SERVER1/cn=Micros
   oft DSA:SERVER1.
   Messages could not be sent. Make sure that the MTA on this Microsoft
   Exchange Server computer is running.

   Event ID 3139 Source:MSExchangeDS Category:Replication

   An internal MTA error occurred. An open function mismatch occurred with
   the directory. Entity name: . [XAPI MAIN BASE 1 92] (14)

NOTE: This problem will only be seen on Directory Replication bridgehead servers.

When you view the properties of this server, it will be reported as an Exchange Server 5.5 computer because of directory replication backfill. Intrasite directory replication will be successful, but intersite will fail.

CAUSE

This problem is caused because of the change in the way the directory replication communicates with the message transfer agent (MTA) in Exchange Server 4.0 and with the Information Store in Exchange Server 5.0 and Exchange Server 5.5. Directory replication backfill causes the Exchange Server computer to function as an Exchange Server 5.5 server computer, whereas the Exchange Server 4.0 executable files do not support this behavior.

WORKAROUND

To work around this problem, providing an Exchange Server 5.5 server computer exists in the site, it is possible to have this server participate in directory replication again by using the Authoritative Restore utility (authrest.exe).

This utility should be used on a directory that was backed up prior to the upgrade. It is used after restoring the directory to that server before starting the services. For clarification, see the example scenario in the More Information section below.

If an Exchange Server 5.5 server computer does not exist in the site, replication will work. However, you will not be able to create users as the updated schema will expect Exchange Server 5.5 proxy DLLs, so it will be necessary to either upgrade again immediately after fixing the original problem, or install a new Exchange Server 5.5 server computer into the site. Alternatively, editing the raw-mode values for proxy generators should correct this problem.

For more information, please see the following Microsoft Knowledge Base article:

158336 XADM: Modifying Version Values for Proxy Address Generator.

MORE INFORMATION

In this example scenario, one site has three servers; A, B, and C. ServerA and ServerC are running Exchange Server 4.0 Service Pack 4. ServerB is running Exchange Server 5.5. ServerA is connected through an X.400 Connector to another server, ServerD, in another site, and all are replicating. Upgrade ServerA to Exchange Server 5.5 and allow this change to replicate around the site and between sites. Then remove Exchange 5.5 from ServerA and reinstall 4.0 Service Pack 4, choose to create a new Site with the same Organization and Site names, and then restore the Exchange Server 4.0 Service Pack 4 Dir.edb file. Check replication. Intrasite replication will work, but intersite replication with ServerD will fail. You will see event 3139 in the Windows NT Event Viewer and you will see replication messages NDR.

To get this working, you will need to uninstall ServerA, and reinstall Exchange Server 4.0 Service Pack 4 again. Choose to create a new Site during setup and use the same Organization and Site names. Then restore the Exchange Server 4.0 Service Pack 4 Dir.edb file. Copy Authrest.exe off the Exchange Server 4.0 CD, and run the following command from an MS-DOS command prompt on the Exchange Server computer:

authrest 1000 1000

Then check intrasite and intersite replication. They should both work correctly.

If the server to be backed out is not a directory replication bridgehead server, and an Exchange Server 5.5 server computer exists in the site, you will experience no directory replication problems, although the server will report as being an Exchange Server 5.5 computer through the Exchange Server Administrator program. It is recommended to upgrade as soon as possible.

If the site affected is single server, the server will appear as the correct version locally, but as an Exchange Server 5.5 server computer to the rest of the organization until the directory replication connector is broken and recreated.