I am configuring a mongodb replica set. From my current primary node, when rs.add('host1:27017'), it yields this error

Quorum check failed because not enough voting nodes responded; required 2 but only the following 1 voting nodes responded; the following nodes did not respond affirmatively; failed with Server min and max wire version are incompatible (7,7) with client min wire version (6,6)

On my host1 and host2 machines, I already added replication option with the same replSetName, bind_ip, and exposed firewall. As a proof, through command line mongo --host host1 I can still connect to host1's mongo instance. The telnet command also yields the same successful connection. I don't know how to fix this.

  • The error message regarding wire protocol version suggests that you are trying to mix 3.6 and 4.0 members in a replica set, where the 4.0 member is likely running with featureCompatibilityVersion set to 4.0. For a new replica set you should ideally start with all members on the same version. Also note that the bind_ip option is not a firewall. It should contain the local IPs each instance is listening to, which would generally be different on each instance unless you are using bindIpAll.
    – Stennie
    Commented Jul 22, 2019 at 1:14

1 Answer 1


The answer is that all 3 machines must have the same version 4.0

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