Too Many Folders To Successfully Migrate To Exchange Online


Exchange Online has a limit of 10,000 folders within a mailbox. If you try and migrate a mailbox with more than this number of folders then it will fail – and that would be expected. But what happens if you have a mailbox with less than this number of folders and it still fails for this same reason? This is the problem, with resolution, I outline below.

I was moving some mailboxes to Exchange Online when I came across the following error in the migration batch results:

Data migrated: 18.18 MB ‎(19,060,890 bytes)‎
Migration rate: 0 B ‎(0 bytes)‎
Error: MigrationMRSPermanentException: Error: Could not create folder 2288. –> MapiExceptionFolderHierarchyChildrenCountQuotaExceeded: Unable to create folder. ‎(hr=0x80004005, ec=1253)‎ Diagnostic context: Lid: 55847 EMSMDBPOOL.EcPoolSessionDoRpc called [length=204] Lid: 43559 EMSMDBPOOL.EcPoolSessionDoRpc returned [ec=0x0][length=468][latency=1] Lid: 52176 ClientVersion: 15.20.1730.17 Lid: 50032 ServerVersion: 15.20.1730.6019 Lid: 35180 Lid: 23226 — ROP Parse Start — Lid: 27962 ROP: ropCreateFolder [28] Lid: 17082 ROP Error: 0x4E5 Lid: 25953 Lid: 21921 StoreEc: 0x4E5 Lid: 27962 ROP: ropExtendedError [250] Lid: 1494 —- Remote Context Beg —- Lid: 38698 Lid: 29818 dwParam: 0x0 Msg: f28f1e21-62aa-4999-977f-ce310efea309-61f0997f-74d5-4421-9050-64f8272e5ac2[9]-28A06 Lid: 29920 dwParam: 0xB Lid: 29828 qdwParam: 0x2711 Lid: 29832 qdwParam: 0x2710 Lid: 45884 StoreEc: 0x4E5 Lid: 29876 StoreEc: 0x4E5 Lid: 30344 StoreEc: 0x4E5 Lid: 54080 StoreEc: 0x4E5 Lid: 56384 StoreEc: 0x4E5 Lid: 38201 StoreEc: 0x4E5 Lid: 35904 Lid: 45434 Guid: f12f3e45-67aa-89012-345f-ce678efea901 Lid: 10786 dwParam: 0x0 Msg: 15.20.1730.017:VI1PR0502MB2975:145a3769-3902-4e6b-9fe4-6db564e4eb92 Lid: 1750 —- Remote Context End —- Lid: 31418 — ROP Parse Done — Lid: 22417 Lid: 30609 StoreEc: 0x4E5 Lid: 29073 Lid: 20369 StoreEc: 0x4E5 Lid: 64464 Lid: 64624 StoreEc: 0x4E5

In the above I have highlighted some of the errors I was seeing – with the “could not create folder” message, the first indicator is that I have too many folders to migrate or I have a corrupt mailbox. Running Get-MoveRequestStatistics and including a full report (with -IncludeReport) shows in part the below. This was run to get more info on the move request. This was run from Exchange Online:

​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​26/03/2019 17:10:09 [VI1PR0502MB3855] ‘MigrationService (on behalf of ‘Brian.Reid@domain.co.uk’)’ created move request.
26/03/2019 17:10:15 [DB8PR05MB6025] The Microsoft Exchange Mailbox Replication service ‘DB8PR05MB6025.eurprd05.prod.outlook.com’ (15.20.1730.17 ServerCaps:01FFFFFF, ProxyCaps:07FFFFC7FD6DFDBF5FFFFFCB07EFFF, MailboxCaps:, legacyCaps:01FFFFFF) is examining the request.
26/03/2019 17:10:15 [DB8PR05MB6025] Content from the Shard mailbox (Mailbox Guid: f12f3e45-67aa-89012-345f-ce678efea901, Database: cc980daf-4402-4645-b26c-2a83760b161c) will be merged into the target mailbox.
26/03/2019 17:10:15 [DB8PR05MB6025] Connected to target mailbox ‘tenant.onmicrosoft.com\2c065e32-3bd5-4524-9aac-03880fa8e961 (Primary)’, database ‘EURPR05DG090-db014’, Mailbox server ‘DB8PR05MB6025.eurprd05.prod.outlook.com’ Version 15.20 (Build 1730.0).
26/03/2019 17:10:20 [DB8PR05MB6025] Connected to source mailbox ‘tenant.onmicrosoft.com\2c065e32-3bd5-4524-9aac-03880fa8e961 (Primary)’, database ‘DB’, Mailbox server ‘onprem.server.domain.com’ Version 15.0 (Build 847.0), proxy server ‘onprem.server.domain.com’ 15.0.847.40 ServerCaps:, ProxyCaps:, MailboxCaps:, legacyCaps:1FFFCB07FFFF.
26/03/2019 17:10:21 [DB8PR05MB6025] Request processing started.
26/03/2019 17:10:21 [DB8PR05MB6025] Source mailbox information:
Regular Items: 8443, 905.4 MB (949,422,345 bytes)
Regular Deleted Items: 1149, 189.9 MB (199,115,692 bytes)
FAI Items: 4651, 11.72 MB (12,285,701 bytes)
FAI Deleted Items: 9, 19.26 KB (19,721 bytes)
26/03/2019 17:10:21 [DB8PR05MB6025] Cleared sync state for request 2c065e32-3bd5-4524-9aac-03880fa8e961 due to ‘CleanupOrphanedMailbox’.
26/03/2019 17:10:21 [DB8PR05MB6025] Mailbox signature will not be preserved for mailbox ‘tenant.onmicrosoft.com\f12f3e45-67aa-89012-345f-ce678efea901 (Primary)’. Outlook clients will need to restart to access the moved mailbox.
26/03/2019 17:11:20 [DB8PR05MB6025] Stage: CreatingFolderHierarchy. Percent complete: 10.
26/03/2019 17:12:38 [DB8PR05MB6025] Initializing folder hierarchy from mailbox ‘tenant.onmicrosoft.com\2c065e32-3bd5-4524-9aac-03880fa8e961 (Primary)’: 29048 folders total.
26/03/2019 17:21:21 [DB8PR05MB6025] Folder creation progress: 1102 folders created in mailbox ‘tenant.onmicrosoft.com\2c065e32-3bd5-4524-9aac-03880fa8e961 (Primary)’.
26/03/2019 17:31:22 [DB8PR05MB6025] Folder creation progress: 2730 folders created in mailbox ‘tenant.onmicrosoft.com\2c065e32-3bd5-4524-9aac-03880fa8e961 (Primary)’.
26/03/2019 17:41:22 [DB8PR05MB6025] Folder creation progress: 4535 folders created in mailbox ‘tenant.onmicrosoft.com\2c065e32-3bd5-4524-9aac-03880fa8e961 (Primary)’.
26/03/2019 17:51:23 [DB8PR05MB6025] Folder creation progress: 6257 folders created in mailbox ‘tenant.onmicrosoft.com\2c065e32-3bd5-4524-9aac-03880fa8e961 (Primary)’.
26/03/2019 18:01:23 [DB8PR05MB6025] Folder creation progress: 7919 folders created in mailbox ‘tenant.onmicrosoft.com\2c065e32-3bd5-4524-9aac-03880fa8e961 (Primary)’.
26/03/2019 18:11:23 [DB8PR05MB6025] Folder creation progress: 9570 folders created in mailbox ‘tenant.onmicrosoft.com\2c065e32-3bd5-4524-9aac-03880fa8e961 (Primary)’.
26/03/2019 18:14:15 [DB8PR05MB6025] Fatal error StoragePermanentException has occurred

The move request logs show an increasing folder count, and when this exceeds 10,000 a storage error occurs.

So the next thing to do is to check what I have on-premises. I have generally two options to try and fix a mailbox I am moving to Exchange Online. One is to move the mailbox elsewhere on-premises (on the basis that I discard errors on-premises and then move a cleaner mailbox to the cloud) or run repairs on the mailbox. Note that running repairs on-premises is part of the move to the cloud anyway as Exchange Server does this as part of the move.

But this revealed nothing! The move request logs on-premises showed the same – there was over 10,000 folders (indeed some of my mailboxes had over 20,000 folders) and this was enumerated in the move request logs. A New-MailboxRepairRequest did nothing either. But interestingly, Get-MailboxFolderStatistics | Measure showed only 200 folders! Each of my failing mailboxes had between 150 and 263 folders – nothing like the +10,000 that the move request was finding!

So I opened the mailbox in Outlook having granted myself permissions to it – again nothing.

A version of the above cmdlet though indicated something more useful: Get-MailboxFolderStatistics -FolderScope NonIpmRoot | Measure returned a count in excess of 10000.

So I opened MFCMapi and had a look at the folders. Now MFCMapi shows everything in the mailbox, and not just items under the “top of the information store” folder. I went about expanding each subfolder I could find and I came across a subfolder that everytime i expanded it, MFCMapi would hang. I would close and restart MFCMapi and the same thing!

image

I had found my suspect folder – its a iPhone device that had created the +10,000 folders. Now that I had a good candidate for my issue, the fix was easy. I listed the active-sync devices using Get-MobileDevice -Mailbox “Richard Redmond” | FL Identity and then removed the suspect device using Remove-ActiveSyncDevice “domain.co.uk/OU/Richard Redmond/ExchangeActiveSyncDevices/iPhone§A9BCDE7FG57HIJ81KL1M08NOPQ” -Confirm:$false where the device identity was returned in the Get-MobileDevice cmdlet run just before.

This Remove-ActiveSyncDevice (or Remove-MobileDevice) cleans up this mailbox and deletes the partnership with the device.

Once this was done, I moved the mailbox again and it was ~200 folders and not much higher when including the NonIPMRoot folders and the mailbox moved to Exchange Online without further issue.

Where I tested the move to another Exchange Server database rather than Exchange Online, I found that looking in the move request report (I had prestaged the move and then removed the corrupt mobile device), the move report showed information like the following and all I had done was removed one mobile device from the mailbox!

26/03/2019 17:41:22 [servername] Folder hierarchy changes reported in source ‘Primary (a8c13a2f-535b-d996-908e-ff84b1484a7)’: 200 changed folders, 24080 deleted folders.

From the users perspective, if the phone is an active device and is syncing email, then removing the phone causes it to create a new partnership. If the server allows any device then this is seamless to the user. If the server requires authorization to add a new device, then the user will be told this and service desk/admin will need to approve the device again. So if Allow/Block/Quarantine (ABQ) is not enabled on the server, one wonders if deleting all active sync partnerships before migrating any mailbox is an idea worth considering – there could be mailboxes I have moved that are <10,000 folders but not far from that number and therefore storing up issues for the future!


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Comments

11 responses to “Too Many Folders To Successfully Migrate To Exchange Online”

  1. Michael avatar
    Michael

    Thanks, this was exactly the issue with one of our mailboxes.

  2. Jerod avatar

    Thank you for posting this. I had the exact same issue and your solution worked perfectly for me. Thanks again.

  3. Scott avatar
    Scott

    Another way to find the number of folders on the Device is to user Get-mobileDeviceStatistics command.
    Get-MobileDevice -Mailbox mail@domain.com | Get-MobileDeviceStatistics | fl Identity,DeviceFriendlyName,
    LastSuccessSync, NumberOfFoldersSynced

    It will give the Number of folders for each device
    NumberOfFoldersSynced : 13116

    Then do the remove device.

    1. Lars Kragh-Hvidberg avatar
      Lars Kragh-Hvidberg

      Awesome shortcut. Thanks!

  4. Husain Radhi avatar
    Husain Radhi

    Thanks, this is very helpful. I had same issue with a mailbox which include +10,000. but same error message was repeating even after decreasing the folder count to 1000 only.

    Thanks again

  5. ZD avatar
    ZD

    This really works. Thank you so much!

  6. Oscar avatar
    Oscar

    Brilliant! Thank you!

  7. Pramod Ghuge avatar
    Pramod Ghuge

    Hi Brian,

    This was very helpful. Just one thing though, we now need to use Remove-MobileDevice cmdlet instead of Remove-ActiveSyncDevice in Exchange 2013 or later.

    Thanks,
    Pramod

  8. Matt Kunkel avatar
    Matt Kunkel

    Many thanks! This was a big help and I enjoyed learning a few things along the way.

  9. Matthew Prentice avatar
    Matthew Prentice

    Excellent article. This appears to have resolved our issue. Thank you.

  10. Michael Hansen avatar
    Michael Hansen

    Hit my issue spot on. Clean up the activesyn cdevices solved all of our issues. Thanks so much!

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