Adding a VSphere 6 Host to a VCenter 5.5 Appliance?

Hi guys,

I have a VCenter 5.5 appliance which I am hoping to use to manage a VSphere 6 host. Unfortunately, I just can't add the host. I keep getting the error below:

I've made sure the hosts files on both the host and the Center are correct, I've made sure Lockdown Mode is disabled on both, set the ssl handshake timeout on both is set to 120000, restarted the management agents multiple times on both, made sure the vCenter had a Managed IP Address, basically followed everything in these articles:

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1005803

http://kb.vmware.com/selfservice/search.do?cmd=displayKC&docType=kc&docTypeID=DT_KB_1_1&externalId=1003735

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1027672

http://kb.vmware.com/selfservice/search.do?cmd=displayKC&docType=kc&docTypeID=DT_KB_1_1&externalId=1020210

http://kb.vmware.com/selfservice/search.do?cmd=displayKC&docType=kc&docTypeID=DT_KB_1_1&externalId=1008030

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1003490

So this whole exercise has been very educational for me, but hasn't really gotten me anywhere.

But, then it came to me - can you even manage a vSphere 6 Host from a vCenter 5.5 appliance? Do I need to upgrade my vCenter?

If I CAN manage the v6 host from the v5.5 center, what am I doing wrong or what should I be checking/doing?

Thanks in advance for you help.