NVivo 11 for Windows has many new features like Social Network Analysis and Mind Maps that are not supported in older versions of NVivo like NVivo 10. Due to these reasons, and due to the changes in the database structure between NVivo 11 for Windows and older versions of NVivo, a new project created in NVivo 11 cannot be opened in any earlier version of QSR software, including NVivo 10, NVivo 9, NVivo 8, NVivo 7, NVivo 2 or N6 (NUD*IST 6).
Projects developed using NVivo 10, NVivo 9, NVivo 8, NVivo 7, NVivo 2, NVivo 1, N6 (NUD*IST), N5 or N4 software, can be opened and worked with in NVivo 11. However, following this action, the original copy of the existing project remains unchanged. That means it can still be opened in the QSR software it was originally created in.
Refer to the Help in your NVivo 11 software for further information about how earlier projects are converted.