Delete Exchange 2016 database

Question

Hello,
Environment:
2 mail servers
1 Exchange 2016
1 Exchange 2019
Hybrid

Migration to Exchange 2019 is finished and now I need to uninstall Exchange 2016.

First step is to dismount and delete Exchange 2016 database and than uninstall Exchange 2016 but when I try to delete 2016 database error is:
This mailbox database contains one or more mailboxes…
https://techcommunity.microsoft.com/t5/exchange-team-blog/this-mailbox-database-contains-one-or-more-mailboxes-8230/ba-p/587212

Checking for regular,archive,arbitration.. mailboxes reveals nothing:
Get-Mailbox -Database ex16db01
Get-Mailbox -Archive -Database ex16db01
Get-Mailbox -PublicFolder -Database ex16db01
Get-Mailbox -Arbitration -Database ex16db01

But If I check
Get-Mailbox | where {$_.ArchiveDatabase -eq "<databaseName>"}
Output is:

I assume that this is the reason why I cant delete 2016 server database but Im not sure.
What kind of legacy system mailboxes are this?
If I run command „Get-Mailbox -Arbitration | select name,database“ all system mailboxes are located on 2019 server.

Any advice?

Answer 1

Hi @Andy ,

Not only the health mailbox, but also you need to move the auditlog mailbox to another database before removing the old database.

Run below command in EMS to migrate it.
Get-Mailbox -Database databasename -AuditLog | New-MoveRequest –TargetDatabase DBname

Here's a similar case for you reference.
https://social.technet.microsoft.com/Forums/office/en-US/631ba4c4-fc03-476e-86d6-20ff1121aca5/deleting-default-mailbox-database-exchange-2016?forum=Exch2016Adm

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Answer 2

There is no need to remove those, but if you want to, you can simply delete them.

Once you restart the health monitoring service on the new server they get recreated.

https://learn.microsoft.com/en-us/answers/questions/60635/healthmailbox-cleanup.html

Get-Mailbox -Monitoring | Remove-Mailbox

Make sure you also read this and give the necessary permissions so the AD objects are removed:
https://learn.microsoft.com/en-us/exchange/troubleshoot/administration/remove-mailboxdatabase-cannot-remove-health-mailboxes

Otherwise, remove the AD objects manually

Then restart the Microsoft Exchange Health Manager, MSExchangeHM service on each 2019 server to recreate them.

Answer 3

Do those databases still exist?

You can check:

get-mailboxdatabase <guid>

GUID is the value between the {}

If not, you can delete the corresponding System Mailbox.

Answer 4

OK
I found something else....
According to this article monitoring system mailboxes need to be disabled before delete database
https://www.alitajran.com/cannot-delete-mailbox-database-exchange-2016/
and Audit Log mailbox need to be migrated
Where I can find official Microsoft KB about disabling monitoring mailboxes?

Answer 5

Solution
https://learn.microsoft.com/en-US/exchange/troubleshoot/administration/error-remove-a-mailbox-database