Failed to start fess service

I followed the installation instructions at

I managed to install elasticsearch and its plugins. ES starts successfully.
… by the way there are still some references to version 8.6.0 of elasticsearch instead of 8.6.2.

However when I try to start FESS I get the following message
Failed to start fess.service: Unit opensearch.service not found.

Any advice?


The document is old… The latest version of Fess supports OpenSearch, not Elasticsearch.