We currently don't have an upgrade zip for upgrading from 6.3.4 to 6.4.0. The latest upgrade zip available is an upgrade zip for upgrading from 6.3.3 to 6.4.0. This means that customers that are on latest 6.3 release (6.3.4) cannot use upgrade tool when doing an upgrade to 6.4.

This applies to both BPMS and BRMS.

See here: https://access.redhat.com/jbossnetwork/restricted/listSoftware.html?product=bpm.suite&downloadType=distributions&version=6.4