Connect-Mailbox and AllowLagacyDNMismatch

I have solved a one case where we wanted to connect (Use the Connect-Mailbox cmdlet to connect a disconnected mailbox to an Active Directory user object.) an archive mailbox to a linked mailbox in Exchange 2013.

Error from EMS:

25- 7- 2014 10-32-07

[PS] C:\>Connect-Mailbox -Identity "Personal Archive - Jan Novak" -Archive -User JanNovak2 -Database "EXDAG1-DB03"
WARNING: An unexpected error has occurred and a Watson dump is being generated: Object reference not set to an instance
 of an object.
Object reference not set to an instance of an object.
    + CategoryInfo          : NotSpecified: (:) [Connect-Mailbox], NullReferenceException
    + FullyQualifiedErrorId : System.NullReferenceException,Microsoft.Exchange.Management.MapiTasks.ConnectMailbox
    + PSComputerName        :

Error from GUI:

The LegacyDN "/o=CONTOSO/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=Jan Novak" of "cb67270a-ada2-472e-94cc-eb7140f3520f" is in use by the following user in Active Directory: "Pepa Novak (new)". The value for LegacyDN must be unique to each user.

Obviously, the LegacyDN attribute was not unique and defended to connect the mailbox.

[PS] C:\> # disconnected archive
[PS] C:\>(Get-mailboxdatabase|Get-Mailboxstatistics|?{$_.DisconnectReason -ne $null -and $_.DisplayName -like "*Jan*"}).LegacyDN
/o=CONTOSO /ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=Jan Novak

[PS] C:\># linked mailbox
[PS] C:\>(Get-mailbox JanNovak2).LegacyDN
/o=contoso/ou=exchange administrative group (fydibohf23spdlt)/cn=recipients/cn=Jan Novak

How to connect mailbox in case this case? According to Technet and Connect-Mailbox (Exchange 2013) there is available a switch:

25- 7- 2014 10-23-48Well, we have available the switch for similar scenario (i.e. AllowLagacyDNMismatch), but it is reserved only for MS use. I do not know why is it so (let me know if you a clue), but it worked for me without problem:

[PS] C:\> Connect-Mailbox -Identity "Personal Archive - Jan Novak" -Archive -User JanNovak2 -Database "EXDAG1-DB03" -AllowLegacyDNMismatch

[PS] C:\> Test-ArchiveConnectivity

RunspaceId               : 7df20326-4fc0-4ca3-877f-5273aea0d5b7
Identity                 :
PrimaryMRMConfiguration  :
PrimaryLastProcessedTime :
ArchiveDomain            :
ArchiveDatabase          : EXDAG1-DB03
ArchiveMRMConfiguration  :
ArchiveLastProcessedTime :
ComplianceConfiguration  : ElcV2
ItemMRMProperties        :
Result                   : Successfully logged on to the users Archive mailbox.
Error                    :
IsValid                  : True
ObjectState              : New


Let me publish my script which tests and gathers information directly from Exchange server 2010 (Windows 2008). It is my little helper in case of patching or troubleshooting. Basically it is nothing special, but let’s look at its help:

    Test-ExchangeServer2010.ps1 - - v1.180714
    This script performs test cmdlets and gathers information from Exchange Server 2010 (Windows Server 2008) into own txt log.
    It can be used only directly on the Exchanger server (the server role is chosen automatically). 
    Only get and test cmdlets are used for this type of health check.
    Run-space: PowerShell 2.0 or Exchange Management Shell.
    Prerequisite: new-TestCasConnectivityUser.ps1
    Tests and information:
        - Get-WMIObject (Operating System, Volumes)
        - Get-ExchangeServer
        - GCM Exsetup
        - Test-ServiceHealth
        - Get-ExchangeCertificate
        - IIS Status
        - Test-PowerShellConnectivity
        - Test-FederationTrust
        - Server Services
        - Bad Application Events
        - Bad System Evenets
        - Top processes - CPU,MemorySize
        - Server Performance
      Mailbox role:
        - Get-MailboxDatabaseCopyStatus
        - Get-DatabaseAvailabilityGroup
        - Cluster /quorum
        - Cluster group /stat
        - Cluster /prop
        - Test-Mailflow
        - Test-MAPIConnectivity
        - Test-ReplicationHealth
      CAS role:
        - Test-OwaConnectivity
        - Test-ActiveSyncConnectivity
        - Test-WebServicesConnectivity
        - Test-OutlookWebServices
        - Test-OutlookWebServices
        - Test-OutlookConnectivity
        - Test-EcpConnectivity
        - Test-ImapConnectivity
        - Test-PopConnectivity
      HUB role:
        - Test-SmtpConnectivity
        - Get-Queue
    # It performs test cmdlets and gathers information into txt log generated in C:\temp.
    Test-ExchangeServer.ps1 -ShowOutputLog
    # It performs test cmdlets and gathers information into txt log generated in C:\temp and opens the log in notepad at the end.
    Test-ExchangeServer.ps1 -OutputLogPath "D:\Report\ExchangeServerLog.txt"
    # It performs test cmdlets and gathers information into the specified log file.
    Test-ExchangeServer.ps1 -ShowOutputLog -OutputLogPath "D:\Report\ExchangeServerLog.txt"
    # It performs test cmdlets and gathers information into the specified log file and opens the log in notepad at the end.

How to use it?

Just copy the script to your Exchange server and go ahead:

19- 7- 2014 13-07-58Output log as its result:

19- 7- 2014 13-17-56How to compare logs (i.e. check the state before/after patching)?

For example via Total Commander:

19- 7- 2014 12-50-56Download: Test-ExchangeServer2010.ps1 –