Spotfire Server: "CSR was rejected by the server Node" error causes failure to trust a Node Manager node

Summary:
Error "The CSR was rejected by the server Node" may result in a failure to trust a node in Spotfire Server. This may be caused by nodemanager.properties having an incorrect backend communication port for the Spotfire Server.

Details:
When trying to trust a node, we may see the following error and the node cannot be trusted:

nodemanager.trust.CertificateMonitor: The CSR was rejected by the server Node [serverId=c8ca80cb-752f-4918-b1bb-46d273a292e5, serverName=<server name>, port=9443, online=true, siteID=5c2c7b84-e1f4-4187-9799-85a2a48f0ebc]. It may already have a CSR for this node.

Resolution:
The reason for this behavior is that the nodemanager.properties may have incorrect backend communication port information for the Spotfire Server. The registration port may, however, be correct which is why the node appears in the untrusted nodes tab. 

To resolve the issue, update the nodemanager.properties file with the correct backend communication port that was used during the installation.