Read the release notes for this release to determine how to migrate the
database to the new version. Generally, this is done via the 'p4d -xu'
command.

http://www.perforce.com/perforce/doc.current/user/relnotes.txt

It is highly recommended that you checkpoint the server (with the old
binary) before you attempt an upgrade; please be sure you have valid
backups of your database before you go any further.