Issue: The Exchange move mailbox process fails at “/Reminders” on one or more users mailboxes
Solution: cleanup and remove corrupt Outlook data preventing mailbox from Migrating
1) Connect to the problem mailbox using the MFCMAPI tool
2) ‘Hard Delete’ the TO-DO Search Folder, close MFCMAPI
3) Run “Outlook /cleanfinders”, close Outlook (see using Outlook’s clean /switches for the complete commands)
4) Run “Outlook /cleanreminders”, close Outlook
5) Run “Outlook /cleanfreebusy”, close Outlook
6) Run “Outlook /cleanviews”, close Outlook
7) Cancel the previous move request and move the mailbox again
If migration still fails, try these steps:
1) enable permission inheritance in AD
Resources: https://social.technet.microsoft.com/Forums/en-US/89902f00-4b84-4f10-b909-121a81241c85/can-not-move-exchange-2003-mailboxes-to-exchange-2010?forum=exchangesvrdeploylegacy