Upgrading SEE from 8.2.1 to 11

I have tried upgrading a client from version 8.2.1 of Symantec Endpoint Encryption to version 11 and have had no success. Is there something I can do without having to decrypt the hard drive uninstall version 8 and reencrypt. If we have to do this for every client that has version 8, this would be a very very long procedure.

Thanks,

Storm