[[setup-upgrade]] == Upgrading Elasticsearch [IMPORTANT] =========================================== Before upgrading Elasticsearch: * Consult the <> docs. * Test upgrades in a dev environment before upgrading your production cluster. * Always <> before upgrading. You **cannot roll back** to an earlier version unless you have a backup of your data. * If you are using custom plugins, check that a compatible version is available. =========================================== Elasticsearch can usually be upgraded using a rolling upgrade process, resulting in no interruption of service. This section details how to perform both rolling upgrades and upgrades with full cluster restarts. To determine whether a rolling upgrade is supported for your release, please consult this table: [cols="1> |5.x |5.y |<> (where `y > x`) |5.x |6.x |<> |6.0.0 pre GA |6.x |<> |6.x |6.y |<> (where `y > x`) |======================================================================= [IMPORTANT] .Indices created in Elasticsearch 2.x or before =============================================== Elasticsearch is able to read indices created in the *previous major version only*. For instance, Elasticsearch 6.x can use indices created in Elasticsearch 5.x, but not those created in Elasticsearch 2.x or before. This condition also applies to indices backed up with <>. If an index was originally created in 2.x, it cannot be restored into a 6.x cluster even if the snapshot was made by a 5.x cluster. Elasticsearch 6.x nodes will fail to start in the presence of too old indices. See <> for more information about how to upgrade old indices. =============================================== include::rolling_upgrade.asciidoc[] include::cluster_restart.asciidoc[] include::reindex_upgrade.asciidoc[]