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This issue occurs if the mailbox database that hosts the Offline Address Book (OAB) generation mailbox has multiple copies and if some copies aren't healthy or available. 

Additionally, when this issue occurs, you may encounter one or more of following problems:

  • The scheduled OAB generation doesn't occur.

  • If OAB generation is forced by calling the Update-OfflineAddressBook cmdlet, the command is completed successfully. However, the OAB distribution folder isn't updated.

  • There are no warning or error events in the Application log about the OAB generation failure.

  • The OAB generation logs aren't updated at all. (You can find these logs in the \Logging\OABGeneratorLog folder.)


This issue occurs because System Workload Management (WLM) throttles OAB generator tasks if a resource crunch occurs on the server.


To work around this issue, use one of the following methods. 

Method 1

Wait until the database copy becomes healthy and WLM workloads are underloaded.

Temporarily disable the workloads that are preventing the OAB generation. To do this, follow these steps:

  1. Add monitoring overrides for the resource monitors to turn off Mailbox Database Availability Health and Mailbox Database Replication Health temporarily until the first server is available. To do this, run the following commands:
    New-SettingOverride -Name MdbAvailability -Component WorkloadManagement -Section MdbAvailability -Parameters @("Enabled=false") -Reason "Temporarily turning off MdbAvailability to generate Offline Address Book" -Server <Server Name where the database is mounted> New-SettingOverride -Name MdbReplication -Component WorkloadManagement -Section MdbReplication -Parameters @("Enabled=false") -Reason "Temporarily turning off MdbReplication to generate Offline Address Book" -Server <Server Name where the database is mounted> Notes

    • In these commands, replace the string in angle brackets (<>) with the name of the server where the database is mounted.

    • The overrides will be effective 15 minutes after Active Directory replication.

  2. Generate the OAB by running the following command:Update-OfflineAddressBook -Identity <Offline Address Book Name>

  3. Remove the overrides by running the following commands after OAB generation is complete:
    Remove-SettingOverride MdbReplication Remove-SettingOverride MdbAvailability

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