The version of etcdcluster is "not_decided", why?

One of the nodes' etcdcluster version is as followed:
# curl http://127.0.0.1:2380/version
{"etcdserver":"3.2.7","etcdcluster":"not_decided"}

And the other nodes of etcd are restarting all the time, because they cannot understand the cluster version of "not_decided".

Is there any way to specify the etcdcluster's version? Any answer will be appriciated, and thanks in advance.

There are less than half of members in etcdcluster survived, so they cannot decide the cluster ID.