Adding 5th node getting an error

"Our replica set configuration is invalid or does not include us

Presently all 4 nodes are healthy.

node arb1 arb2
rs1 m1,m2,m2 a1

when I try to add a2 both the arbiters will go unhealhty immediately whereas my arbiter is healhty on itself but not healthy in replica set.

node arb1 arb2
rs1 m1,m2,m2 a1 a2

Error for arbiter in replica set -

a1 - "lastHeartbeatMessage" : "Our replica set configuration is invalid or does not include us"

a2 - "lastHeartbeatMessage" : "Couldn't get a connection within the time limit"


m- data nodes

a- arbiters


2 Answers 2


Replica set should have ONLY one arbiter and ONLY when there is an even number of data-bearing nodes.

Your replica set has already an odd number of data-bearing nodes (m1, m2, and m3), so there should not be any arbiters.

Those error messages means:

a1 - rs.conf() don't have that a1 node in the list of that replica sets' config, it may have wrong IP or port-number
a2 - there is firewall (or similar) what prevents connection with other RS nodes.
  • you are right it was a wrong name resolution
    – unknown
    Jul 7, 2021 at 12:50

Use bellow code before adding arbiter to cluster

    setDefaultRWConcern : 1,
    defaultWriteConcern: { w: 1 },

After this add arbiter to cluster


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