Java recommendation for SolrFor verions from 6.0.0 through 9.0.0, I would recommend Java 11. For 9.1.0 or later, I would recommend Java 17. Not sure I can recommend running any Solr version below 6.0.0. Java 17 is noticeably faster than Java 11 in my small-scale experiments. In the past I would have strongly recommended never using an IBM Java. I don't know if that is still a good idea or not.