Tableau Server with Multi-Node Elasticsearch Fails to Start in 2020.4.x+

Issue

When installing or upgrading to Tableau Server 2020.4 on a multi-node Tableau Server deployment which has Elasticserver (Elasticsearch) on more than one node, Tableau may fail to start. This blocks upgrade/installation.

Environment

Tableau Server 2020.4.x
Elasticserver (Elasticsearch) installed on more than one node

Resolution

If you are installing or upgrading to Tableau Server 2020.4 and Elasticserver fails to come up, please reach out to Tableau Support at Support & Services (tableau.com).

To help with diagnosis, please provide the following:

The config/elasticsearch.yml file
The Elasticserver logs
The hostname(s) of the machine(s) with the issue

Workaround

If you are running Elasticsearch on multiple nodes, the workaround is to change your topology to a single-node of Elasticsearch only. This is sufficient and will still support the vast majority of necessary workloads.

Cause

A known root cause is that if the hostname of a machine is capitalized in a particular way, Elasticsearch's multi-node clustering algorithm fails to discover its peer nodes and fails to form a cluster.