I also faced the same problem!!!!
It is recommended to upgrade the nodes after breaking the cluster.See KB KB76905
So break the cluster,upgrade individually & then add in cluster.All webgateway needs to be of same version
problem is that we already can't access web GUI, is possible node remove from cluster via command line?
I dont know how to remove it from cluster via command line.
But even if u are able to break it via command line how will u get the GUI???
Since u upgraded the webgateway,it cant b degraded,so u need to reimage the webgateway.
If there is any other way then support team might help u
Hello so we got it sorted, problem was that in server.xml was missing configuration of IP where mwg-ui should listen.
Not sure if problem was caused by upgrade, but after reboot was appliance unable to bind any available network interface with error:
LifecycleException: service.getName(): "Konfigurator"; Protocol handler start failed: java.lang.Exception: Socket bind failed:  Address already in use
Despite the fact that nothing was at this time listening on this port. After we manually updated server.xml and reloaded mwg-ui we were able to connect via web interface again.
Many thanks for all help, is really appreciated.
Ok ,gud!!!Thats great
May be u have some diff error...
Could u please elaborate what exactly u did