These events are logged when the EnableOabGenOnThisNode registry entry is missing or when the registry entry contains an invalid server name.

On an Exchange 2007 server that is running Cluster Continuous Replication (CCR), the following registry subkey controls which CCR cluster node generates and updates the OAB data files:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeSA\Parameters\<ServerName>\EnableOabGenOnThisNode

By default, the EnableOabGenOnThisNode value is the name of the CCR node that was installed first. This node is also known as the primary node. OAB generation or OAB updates may fail if one of the following conditions is true:

• The EnableOabGenOnThisNode registry entry is missing.
  
  
• The EnableOabGenOnThisNode registry entry contains an invalid name. For example, the registry entry contains the name of a server that is no longer the active node of the CCR cluster.
  
  

Note:
Incorrectly editing the registry can cause serious problems that may require you to reinstall your operating system. Problems resulting from editing the registry incorrectly may not be able to be resolved. Before editing the registry, back up any valuable data.

To resolve this issue, follow these steps:

1. Start Registry Editor on each CCR node, and then verify that the following registry subkey is present:
   
   HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeSA\Parameters\<ServerName>\EnableOabGenOnThisNode
   
   If the registry entry does not exist, create the following registry entry:
   
   Value name: EnableOabGenOnThisNode
   
   Value type: REG_SZ
   
   Value data: primary CCR node name
   
   
2. Verify that the EnableOabGenOnThisNode value is set to the host name of a valid CCR node. By default, the registry entry is set to the host name of the primary CCR node.
   
   
3. If the CCR node that is specified in the registry entry is offline, bring the CCR node back online, and then configure the CCR node as the primary node again.
   
   
4. If the CCR node cannot be brought back online, change the EnableOabGenOnthisNode value to that of the secondary CCR node. For example, change the registry value to Node2.
   
   
5. By default, OAB generation for public folder distribution runs at 5:00 A.M. each day. To immediately update the OAB for public folder clients, follow these steps:
   
   
   1. On the Mailbox server, start the Exchange Management Console.
      
      
   2. Expand Organization Configuration, and then click Mailbox.
      
      
   3. Click the Offline Address Book tab, right-click the offline address book and then click Update. (By default, the address book is named Default Offline Address Book.)
      
      
   4. Click Yes to confirm that you want to update the OAB.
      
      
   By default, OAB generation for Web-based distribution runs every eight hours. To immediately update the OAB for Web-based distribution, follow these steps:
   
   
   1. Start the Services Microsoft Management Console (MMC) snap-in on the server that runs the Exchange 2007 Client Access server role. To do this, click Start, click Run, type services.msc, and then click OK.
      
      
   2. In the Services list, right-click Microsoft Exchange File Distribution, and then click Restart.
      
      
6. Verify that the OAB was generated successfully. To do this, start a Microsoft Office Outlook 2007 client that is configured to run in Cached Exchange Mode. Then, download the OAB. 
   
   

For more information, see OALGen is running on the wrong CCR cluster node.

For more information about how to create an OAB in Exchange 2007, see How to Create an Offline Address Book.

For more information about how to configure CCR in Exchange 2007, see Cluster Continuous Replication.