[MarioL]

I haven't done cluster upgrades for a while now, but if memory serves, you will need to turn off the old node to get the upgraded one to work. Otherwise the broadcasts will probably create issues.

I bet that if you turn off node B and reboot node A, it will come back up as active. I know it will cause downtime... which might not be acceptable.

Have you tried to force the state to up on the upgraded node?
I can't remember the command now, but it's not the "cphaprob state", it's the other one.

One test you can do is:
- connect all of the upgraded node's nics to dif switches, so they don't interfere with the other node and boot it, check if it boots as up.