Congratulations on a successful migration to a newer version of Exchange Server! Everything seems to be in order as your mailboxes have transitioned smoothly. However, you might be encountering a pesky issue: problems with downloading the Offline Address Book (OAB).

Additionally, any changes made in the online Address Book aren’t showing up in the local copy. This can be frustrating, especially when you expect the address book to reflect new joiners, mailbox removals, email address changes, and even addresses that were previously hidden.

In this blog, we’ll dive into the common challenges that arise with Offline Address Books after an Exchange Server migration. More importantly, we’ll explore effective troubleshooting steps to ensure your address book remains up-to-date and fully functional. Let’s get started on resolving this issue and keeping your communication systems running smoothly.

Resolving “Unable to Download OAB after Migration” Issue

Have you encountered the challenge of users being unable to download the Offline Address Book (OAB) after a migration, despite them reporting no apparent issues? It’s a common scenario where users notice missing addresses or changes in the address book. However, when they attempt to download the OAB, they’re met with an error message like this:

“Task reported error (0x80040104): ‘The operation failed. An object cannot be found.'”

In this guide, we’ll take a methodical approach to diagnose and fix this issue. Let’s start with the first step:

Step 1: Analyze the “Unable to Download OAB after Migration” Issue

While users may not be aware of underlying problems, their experience tells a different story. To tackle this, we need to examine the issue from the server’s perspective.

Here’s how:

User Error Message: When users encounter issues downloading the OAB, they often see an error message like the one mentioned above. It indicates that something is amiss, and we need to dig deeper to find the root cause.

Server-Side Check: To begin, we can run a server-side check to determine if the necessary system mailboxes are in place. These system mailboxes play a crucial role in OAB functionality. Run the command:

Get-Mailbox -Arbitration

This command will provide valuable insights into the server’s health and confirm whether the essential components, particularly the arbitration mailbox, are correctly configured.

By following these initial steps, we lay the groundwork for identifying and resolving the “Unable to Download OAB after Migration” issue. Stay tuned for further steps as we work to get your OAB functioning smoothly again.

Step 2: Troubleshooting the ‘Unable to Download OAB’ Issue

So, you’ve identified the ‘Unable to Download OAB’ issue, and now it’s time to dive into troubleshooting.

Let’s roll up our sleeves and get to the bottom of this problem.

Migration Verification: The first crucial step is to review the migration process. Ensure that you’ve followed a checklist for a successful decommissioning of the old Exchange server. It’s imperative to verify that the old server has been uninstalled correctly after all mailboxes have been migrated. Sometimes, if the arbitration mailbox is still on the old server, it won’t transfer automatically, and services may still point to the outdated server.

Check the OAB Website: Next, investigate the Offline Address Book (OAB) website on the new server. Confirm its existence and check if it’s active and running smoothly. The OAB website is a critical component for OAB functionality.

Verify the OAB Folder: Ensure that the Outlook Address Book (OAB) folder has been created. You can locate this folder under the installation path of the Exchange Server, specifically within the Client Access Folder, and further inside the OAB folder. Typically, you can find it at:

C:\\ClientAccess\oab

If you don’t find a file with the GUID in this location, it’s worth trying to restart the Microsoft Exchange Mailbox Assistant service using this command:

Restart-Service MSExchangeMailboxAssistants

By systematically addressing these troubleshooting steps, you’re well on your way to resolving the ‘Unable to Download OAB’ issue and ensuring that your Offline Address Book operates smoothly. Stay tuned for further guidance as we continue troubleshooting this problem.

Step 3: Attempt to Update the Address Book

Update the Address Book: Start by trying to update the address book. This is a crucial step to ensure that your Offline Address Book (OAB) gets refreshed with the latest information.

Check Event Viewer: If updating the address book doesn’t resolve the issue, it’s time to dig deeper. Check the Event Viewer for any indications or related errors that might point to the specific problem. Event Viewer can be a valuable diagnostic tool in identifying underlying issues.

Confirm Web Page Accessibility: To further troubleshoot, attempt to access an attached image website. This step helps verify network connectivity and accessibility.

• Access the Website: Using a standard web browser, attempt to access the attached image website. It’s important to note that you won’t be able to view the content from a regular browser, but you should at least receive an “access denied” message. This message indicates that the website is reachable from your network.
• Network Troubleshooting: If you don’t receive an “access denied” message and can’t access the website, this might indicate network issues that need to be addressed.

By following these steps, you’re actively working to diagnose and resolve the ‘Unable to Download OAB’ issue. Stay tuned for further guidance as we continue our troubleshooting journey, ensuring that your Offline Address Book operates smoothly.

Step 4: Creating a New Offline Address Book

If the previous steps haven’t resolved the problem, consider creating a new Offline Address Book (OAB) to address the issue.

Here’s how to do it:

Create a New OAB:

Run the following command to create a new OAB with a specific name:

New-OfflineAddressBook -Name "" -AddressLists "Default Global Address List" -GlobalWebDistributionEnabled $true

Set the New OAB as Default:

The next crucial step is to set the newly created address book as the default one, replacing the current OAB. Use this command:

Set-OfflineAddressBook -Identity "" -IsDefault $true

Verify the Default OAB:

Confirm that the new address book is now set as the default by running this command:

Get-OfflineAddressBook | Format-List Name,AddressLists,GeneratingMailbox,IsDefault,VirtualDirectories,GlobalWebDistributionEnabled

Restart Mailbox Assistant Service:

Restart the Microsoft Exchange Mailbox Assistant service once more and carefully monitor for any issues or errors in the Event Viewer.

If the Problem Persists:

If the problem still persists despite these efforts, it’s possible that there are underlying issues with the configuration or installation of the Exchange Server.

Consider Server Restoration:

As a last resort, you can explore restoring the decommissioned server. Alternatively, you may opt to reinstall the same Exchange Server using Recovery Mode, ensuring that you retain the same name and IP address. However, this approach involves data recovery and reinstallation without data loss, which can be a complex and resource-intensive process.

By following these steps, you’re exhaustively addressing the ‘Unable to Download OAB’ issue. Stay tuned for further guidance as we explore potential solutions and ensure the seamless operation of your Offline Address Book.

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