Default folders are duplicated after you migrate mailboxes to Exchange Server 2013 Content provided by Microsoft Applies to: Exchange Server 2013 EnterpriseExchange Server 2013 Standard Edition Select Product Version All Products Cause This issue occurs because of some unhandled errors during the mailbox migration process. Resolution To prevent this issue in a migration, install the following cumulative update: Cumulative Update 8 for Exchange Server 2013Note Users who have already had folders duplicated have to remove them manually. Status Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. Last Updated: Mar 23, 2015 Did this solve your problem? Yes No Tell us what we can do to improve the article Submit Thanks! Your feedback will help us improve the support experience.