I was running on elasticsearch 2.3.1, but I had to upgrade to 5.6.4 (because I wanted to install Kibana/Sense), but ElasticSearch won't start anymore.
This is log from ElasticSearch:
java.lang.IllegalStateException: The index [[cyclone3.mysite_sk/Qf5ccdWNRYKFGs4lBffSAQ]] was created with version [1.2.1] but the minimum compatible version is [2.0.0-beta1]. It should be re-indexed in Elasticsearch 2.x before upgrading to 5.6.4.
And lot of the same errors.
Yes I understand that I need to reindex, but how? And does I lose all data?
THIS IS NOT A DUPLICATE OF ElasticSearch doesn't start after installing 5.6.4 BECAUSE THIS IS ON THE DIFFERENT SERVER