Friday, January 20, 2017

Exchange Server Cross forest Mailbox Move Active Directory error 0x51


I'm working on project cross forest mailboxes migration it was running very smooth while migrating mailboxes from source to target forest, but suddenly customer asked me to move back some of the mailboxes due to some business critical issues. When  started to move back the mailboxes got the following error

An Active Directory error 0x51 occurred when trying to check the suitability of server ''. Error: '
Active directory response: The LDAP server is unavailable.'
    + CategoryInfo          : NotSpecified: (0:Int32) [New-MoveRequest], RemoteTransientException
    + FullyQualifiedErrorId : 2946EE38,Microsoft.Exchange.Management.RecipientTasks.NewMoveRequest
LDAP connectivity is fine either way.

This is the actual issues here:

Forest A to Forest B- mailboxes migration working fine.
Forest B to Forest A - Getting error


\Prepare-MoveRequest.ps1 working fine and it shows all ready for migration mailboxes, when i initiated New-MoveRequest it through the error.

In my scenario customer does not have the Active Directory trust between forest, only we configured DNS and everything fine.

Initially i suspected LDAP communication as error stating, when i checked and telnet the 389 from  Forest A to Forest B and vice versa working as expected.

When i checked the event ID and got the clue with error event ID 6, what is the actual issues which i can not imagine because it is basic requirement for migration and wondering.
After dinging on issues got the root cause that from Forest B to Forest A Global Catalog port tcp/3268 was blocked. Issue with Global Catalog communication from Forest B to Forest A. MailboxReplicationService connection getting failed to connect RemoteGlobalCatalog server.

Telnet getting failed to Forest A Global Catalog servers.

Once i open port in firewall after change  mailbox migration working fine both side.

Now, decided to check everything before taking handover the any projects :)

 You can check the deep dive cross forest migration from here

Thank you!