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Title
Some important things to consider when migrating users with "Reconnect Mailbox" option INTRA-FORE -
Description
In some INTRA-FOREST migration scenarios target users may not have access to their mailboxes immediately after migration session is finished. Also the following error can be traced in Exchange server Event Log where mailboxes are located:
Event ID: 9536 "An ambiguous Mailbox Guid <VALUE> was found on 0x2 mailboxes in the DS. The store cannot map this Mailbox Guid to a unique user". -
Cause
This is due to Global Catalog replication latency.
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Resolution
When performing INTRA-FOREST migration it is recommended to follow these recommendations:
Shortly before, during all migration process as well as for some time after (until AD replication is completed + about 15 min to clear Exchange Information store cache) the following conditions must be met:
1. Source or target user should not attempt to log into the mailbox. If this is not followed Information store can cache incorrect AD user associated with the current MailboxGuid.
2. It is also good idea to restart Information Store service to ensure the cache is cleared properly.