Assume that an offline address book (OAB) was first generated in a Microsoft Exchange Server 2013 environment. When the existing .flt file is larger than two gigabytes (GB), the OAB cannot be rebuilt.
This issue occurs because the OAB file size has reached two GB as an intdata type when it should be a uint data type.
To resolve this issue, install Cumulative Update 7 for Exchange Server 2013.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.