When you try to migrate mailboxes from your on-premises Exchange Online organization to Microsoft Office 365 by using a cutover migration, some mailboxes are not migrated. Additionally, you receive the following error message:
Error: Default folders can't be moved or deleted.
This problem occurs if one or more of the default folders (such as Inbox, Drafts, and Send Items) in an affected mailbox are moved, deleted, or corrupted. This occurs when one or more of the following conditions are true:
Third-party Outlook plug-ins are installed.
Mismanagement of low-level folder editors occurs. This includes folders such as Microsoft Exchange Server MAPI Editor (MFCMAPI).
Memory corruption or disk corruption occurs.
Before you can migrate an affected mailbox by using cutover migration, the default folders in the mailbox must be restored to their default state. To do this, follow these steps.
For Microsoft Outlook 2013 and Outlook 2010
If you haven't already done this, connect to the mailbox by using Outlook.
Close Outlook, and then run outlook.exe /resetfolders.
For more information about how to run Outlook from a command line, see the following articles:
Still need help? Go to Microsoft Community.