Comment 21 for bug 1903531

Looks like a partial upgrading of neutron cluster, neutron-server has a newer version while neutron-agents not. And yes, the backported patch caused such RPC incompatible. But IMO, such partial upgrading is not recommended in a production environment, because neutron-server actually does not do real networking data path work, the agents control the data path flows/iptables/routes and so on. Upgrading neutron-server only looks not so much useful. Secondly, I guess maybe we should announce users every time you try to update/restart/online something, try to do it in a test environment first to see if it works as you expected. Finally the upstream team may have no much time to test all the users' cases, and the upstream code sometimes is buggy. Without any test locally and directly push it to the production environment is not a good idea.