PST import from Exch2010 to Exch2013 - Status FailedMAPI and FailedOther

Hi all,

I did New-MailboxExportRequest -Mailbox ... -FilePath \\....pst from working instance of Exchange 2010 and tried to Import that PST file into Exchange 2013 using Shell. As usual there was Alert that Import PST of mailbox has been queued. It was started by me, etc ...

Few hours later I ran Get-MailboxImportRequestStatistics -Identity test\mailboximport and found StatusDetail=FailedMAPI, PercentComplete=69

Because I'm going to migrate about 30 mailboxes in similar way, could you clarify what the problem is it and how to avoid it?

Thanks,

P.S. another attempt using PowerShell to Import same PST finished on 10% with FailedMAPI (or FailedOther???). Also how to figure out which user\mailboximport??? number relates to specific Import process?