Error when finalizing a batch migration of public folders to Exchange Online

Symptoms

You're using batch migration to migrate Microsoft Exchange Server public folders to Exchange Online. When you finalize the migration from the Exchange admin center or by using the Complete-MigrationBatch cmdlet, you receive the following error message:

The migration batch can't be completed due to one or more users having a last sync date older than 7 days.
    + CategoryInfo          : NotSpecified: (:) [Complete-MigrationBatch], MigrationBatchC...nsientException 
    + FullyQualifiedErrorId : [RequestId=<Request ID>, [FailureCategory=Cmdlet-MigrationBatchCannotBeCom 
   pletedTransientException] 123ABCD0,Microsoft.Exchange.Management.Migration.MigrationService.Batch.CompleteMigrationBatch 
    + PSComputerName        : outlook.office365.com 

Cause

To be able to finalize the migration, a check is made to make sure that all recent public folder migration requests were successfully synchronized. Any problem that prevents the requests from being processed will delay the batch migration and might prevent it from being completed. In this situation, the check will fail and return an error.

Resolution

To fix this issue, follow these steps:

1. Make sure that the status shows as Synced for the migration batch and all public folder mailbox migration requests. To check the status, run the following PowerShell cmdlets:

   • For the migration batch, run Get-MigrationBatch.

     The following screenshot shows an example of the output.

     

   • For all public folder mailbox migration requests, run Get-PublicFolderMailboxMigrationRequest.

     The following screenshot shows an example of the output.

     

   If the status of any migration request is something other than Synced, wait until the status changes to Synced. If the status of any migration request is Failed, investigate the reason for the failure.

2. Check the last synchronization time of the migration batch and all public folder mailbox migration requests.

   • For the migration batch, run the following Get-MigrationBatch cmdlet:

     Get-MigrationBatch |?{$_.MigrationType -like "*PublicFolder*"} | ft *last*sync*
     

     The following screenshot shows an example of the output.

     

   • For all public folder mailbox migration requests, run the following Get-PublicFolderMailboxMigrationRequest cmdlet:

     Get-PublicFolderMailboxMigrationRequest | Get-PublicFolderMailboxMigrationRequestStatistics |ft targetmailbox,*last*sync*
     

     The following screenshot shows an example of the output.

     

   The value of LastSyncedDateTime (for the migration batch) and LastSuccessfulSyncTimestamp (for each migration request) should be within the past seven days. If it is outside the previous week, review the migration requests to make sure that they all were successfully synchronized recently.

   Note: In some cases, the status of the migration batch and all migration requests is Synced, but the LastSyncedDateTime value shows a very old date. For example, the value is 01-01-1601 00:00:00. This might occur because the Mailbox Replication Service hasn't updated the migration batch. In this case, wait up to one hour, and then recheck the value of LastSyncedDateTime.

3. Run the Complete-MigrationBatch cmdlet to finalize the migration batch.