I just did a convoluted upgrade from ZCS 4.5.9 to 5.0.4, then RHEL 4.6 to 5.2, then ZCS 5.0.4 to 5.0.7. It worked fine. I did it that way because that is the way I had tested it previously and knew it would work.
My HTTP hostname and cert differ from my actual server hostname, so while on 5.0.4 I did:
Code:
zmlocalconfig -e zimbra_require_interprocess_security=0
which modified zimbra/conf/localconfig.xml. Then, unlike on my testbox, the upgrade to 5.0.7 worked without error.