Couchbase server community 5.0.1 on Ubuntu 16.04 fails to join cluster

I am trying to stand up a cluster of two Couchbase servers running on ubuntu 16.04 VMs in an Open Stack cluster. The Open Stack Security Group has been setup with all of the ports for Couchbase.

I install the community server 5.0.1 and create a cluster on machine A (IP address of, it creates fine. I do not set up any buckets or indexes.

I then go to machine B (IP address of and install the same package. I go to the web interface and select Join a Cluster. I enter in the IP address of Machine A, enter the username and password for the cluster and hit “Join with Default Configuration”. It spins for a bit and then gives this error:

Attention: Join completion call failed. Got HTTP status 500 from REST call post to Body was: “[“Unexpected server error, request logged.”]”

These installs are fresh installs.

I have been trying to find the answer through google searches to no avail so I came here. What am I doing wrong?

It never fails. Post a problem and you find the solution.

The problem was that there was a firewall on one of the machines that didn’t have all of the ports in it. When that firewall was disabled, the node joined right up.