MSExchange ActiveSync 1023 warning

You are getting the Event ID 1023 MSExchange ActiveSync warning in the Event Viewer on the Exchange Server. The Event ID 1023 warning shows: Exchange ActiveSync tried to access a mailbox on Mailbox server. It could not access the mailbox because the Mailbox server is offline. In this article, we will look at why it’s happening and the solution to MSExchange ActiveSync Warning 1023.

MSExchange ActiveSync 1023 warning in Event Viewer

System Center Operations Manager (SCOM) or another monitoring system is sending alerts, and you like to know what is happening. Let’s have a look at the system.

Sign in to Exchange Server and start Event Viewer. Expand Windows Logs and click Application. You will see the Event 1023 MSExchange ActiveSync warnings.

The solution to MSExchange ActiveSync 1023

Run Exchange Management Shell as administrator. Make use of the Get-MailboxDatabase cmdlet. Read the article Get Exchange mailbox database mount status with PowerShell, if you want to learn more.

[PS] C:\>Get-MailboxDatabase -Status | Sort Name | Format-Table Name, Server, Mounted

Name Server    Mounted
---- ------    -------
DB01 EX01-2016    True
DB02 EX01-2016    True
DB03 EX01-2016    True
DB04 EX01-2016    True
DB05 EX01-2016   False

Mailbox Database DB05 is not mounted. The mounted status is showing False. Mount the database and verify the database status.

[PS] C:\>Mount-Database -Identity "DB05" -Confirm:$False

[PS] C:\>Get-MailboxDatabase -Status "DB05" | Format-Table Name, Server, Mounted

Name Server    Mounted
---- ------    -------
DB05 EX01-2016    True

We are going to find all the mailboxes in the database that we mounted.

[PS] C:\>Get-Mailbox -Database "DB05"

Name        Alias       ServerName ProhibitSendQuota
----        -----       ---------- -----------------
Lauren Hill lauren.hill ex01-2016  Unlimited

The next step is moving the mailbox to another database with PowerShell. We are going to move the user to the database DB01.

[PS] C:\>New-MoveRequest -Identity "Lauren Hill" -TargetDatabase "DB01"

DisplayName StatusDetail        TotalMailboxSize         TotalArchiveSize PercentComplete
----------- ------------        ----------------         ---------------- ---------------
Lauren Hill WaitingForJobPickup 483.2 KB (494,806 bytes)                  0

Check the move status and if it’s completed.

[PS] C:\>Get-MoveRequest | Get-MoveRequestStatistics

DisplayName   StatusDetail TotalMailboxSize         TotalArchiveSize PercentComplete
-----------   ------------ ----------------         ---------------- ---------------
Lauren Hill   Completed    483.2 KB (494,806 bytes)                  100

The move request completed successfully. Check if there are mailboxes in the database.

[PS] C:\>Get-Mailbox -Database "DB05"

There is no output shown because there are no mailboxes in the database. Dismount the database and verify if the database is dismounted.

[PS] C:\>Dismount-Database -Identity "DB05" -Confirm:$False

[PS] C:\>Get-MailboxDatabase -Status "DB05" | Format-Table Name, Server, Mounted

Name Server    Mounted
---- ------    -------
DB05 EX01-2016   False

The database is dismounted. Now that there are no users in the database, you will not get the events anymore: Event ID 1023 MSExchange ActiveSync warning. Exchange ActiveSync tried to access a mailbox on Mailbox server. It could not access the mailbox because the Mailbox server is offline.

Read more: MSExchange Mailbox Replication 1006 warning »

Conclusion

To sum it up, you learned why the MSExchange ActiveSync 1023 warning shows up. You also learned the solution to it. Before dismounting the database, make sure to move all the mailboxes to another database. It’s good that Exchange Server is giving a warning in the Event Viewer.

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