It would probably be best to start a new question for this, but... If you have three different CAs that were used to generate three different certs for each of your standalone nodes, then you will need to create a single truststore that has the public keys of all three CAs, and each NiFi node will need to use that trutstore in order to trust the other nodes. The initial admin identity must be the same on all nodes. If you have a client cert that worked on one of your standalone nodes, and if you do what I described above with the truststore, then you can still use this client cert. Each node, will need all the node identities listed. You will also need to delete the users.xml and authorizations.xml from each node so that it starts over. ... View more