Exchange 2016 CU1 and CU2 Mailbox AutoProvision Bug

I have found a bug in Exchange 2016 CU1 and CU2 where mailbox autoprovision places newly created mailboxes on the newest Mailbox Database.

For instance if you have 6 databases, with DB06 being the newest one, Exchange will choose that particular DB for autoprovision.

If you delete a DB, say DB06, and create DB07 Exchange will choose DB07 for all new mailboxes.

I am currently working a Microsoft Support Engineer, who is in turn working with MS Escalation Engineers and MS Product Support to see about getting a fix.

Stay tuned for updates :)

Update 8JUL16: Microsoft has confirmed the AutoProvision bug is present in Exchange 2016 CU1 and CU2.

The Exchange Product Team will institute a fix in the next CU release.

***That means we all have to manually specify a Mailbox Database when creating new mailboxes.
-or-
Create a batch of new mailboxes and manually rebalance them across databases.

So, if you use an onboarding script, you'll need to edit it to make sure it balances the mailboxes manually, or else you'll find that they all got created on one DB!***

Good job testing CU's before releasing them, Microsoft < sarcasm >