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The warning Exchange database is mandatory on UserMailbox is showing in Exchange Admin Center. It’s showing the warning in the details pane after selecting the user in the mailboxes list view. After calling the user, we can confirm that she can’t sign in to her mailbox. What is the solution to Exchange database is mandatory on UserMailbox warning?
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Database is mandatory on UserMailbox warning
Before we start, it’s good to reproduce the issue. First, let’s see what is happening in the Exchange Admin Center (EAC). After that, we will check the status in Exchange Management Shell (EMS).
Check database is mandatory warning in Exchange Admin Center
Sign in to the EAC with administrator privileges. Click recipients in the feature pane and follow with mailboxes in the tabs. Click the user in the list view. In the details pane, we can see the warning: There are multiple warnings. Click here to see more.
Click on the yellow warning to see more.
The warning shows that the user mailbox is corrupted.
The object exoip.local/Users/Administrator has been corrupted or isn’t compatible with Microsoft support requirements, and it’s in an inconsistent state. The following validation errors happened:
Database is mandatory on UserMailbox.
Check database is mandatory warning in Exchange Management Shell
Now that we have seen the warning in EAC. It’s good to check what’s showing in EMS.
We are going to make use of the Get-Mailbox cmdlet and the -Identity parameter.
[PS] C:\>Get-Mailbox -Identity "Kylie Davidson" | fl Database Database : WARNING: The object exoip.local/Company/Users/Sales/Kylie Davidson has been corrupted or isn't compatible with Microsoft support requirements, and it's in an inconsistent state. The following validation errors happened: WARNING: Database is mandatory on UserMailbox. WARNING: Database is mandatory on UserMailbox.
The same warning is showing. WARNING: The object has been corrupted or isn’t compatible with Microsoft support requirements, and it’s in an inconsistent state. The following validation errors happened: WARNING: Database is mandatory on UserMailbox.
Check HomeMDB attribute in ADSI Edit
Sign in to the domain controller and navigate to the Start menu. Open Administrative Tools and start ADSI Edit.
Once opened, right-click ADSI Edit and click Connect to…
Select Default naming context and click OK.
Expand the OU where the user object is configured. In my example, the user is onfigured in the OU=Sales. Right-click the user and click Properties.
In the Attribute Editor tab, search for attribute homeMDB. We can see that the value is <not set>.
A mailbox that is configured in Exchange Server, needs to have a homeMDB. This attribute contains the mailbox database where the object will be assigned a mailbox (e-mail account).
Solution to Exchange database is mandatory on UserMailbox
Have a look at the mailboxes in EAC. Make sure that you select a user mailbox that does not have the database is mandatory on UserMailbox warning. After you find a user, the next step is to find the user in ADSI Edit.
Right-click the user object that you searched for in the previous step. Again, this user does not have that warning. Search for homeMDB and double-click it.
Copy the Value and click twice on OK.
Go to the user object with the <not set> value. That’s the user with the warning. Right-click and click Properties.
Search for HomeMDB and double-click on it.
Paste the copied value. Click OK.
Confirm that the value is set. Click OK.
For the changes to take effect, we need to wait a couple of hours. We can force that by restarting the Exchange Information Store.
If there are mailboxes configured on other mailbox databases in the same Exchange Server, restart the service after working hours. All the users that have their mailbox on the effected databases will lose their Outlook Connection for a short moment. If the Exchange Server is configured in a DAG, you can perform a server switchover and restart the service.
Start Windows Services and select Microsoft Exchange Information Store. Click Restart the service.
Verify the results
Verify the results in both EAC and EMS.
Sign in to the EAC and click the mailbox in the list view. There is no warning anymore in the details pane.
Run the cmdlet to check in which database the user mailbox is configured.
[PS] C:\>Get-mailbox -Identity "Kylie Davidson" | fl Database Database : DB01
It’s looking great. The user can now sign in to her mailbox account.
Did it help you to fix the warning Exchange database is mandatory on UserMailbox warning?
In this article, you learned about Exchange database is mandatory on UserMailbox warning. The solution to this warning is to have a look in ADSI Edit. In ADSI Edit verify that the homeMDB attribute value is not set for the user object. Copy the homeMDB attribute value of another user object. After that, paste the value in the user object with the warning. Restart the Exchange Information Store service for changes to take effect. As of last, verify the results in both Exchange Admin Center and in Exchange Management Shell.