Upgrading Elasticsearch

Upgrading Elasticsearch | Elasticsearch Reference [5.6] | Elastic https://www.elastic.co/guide/en/elasticsearch/reference/5.6/setup-upgrade.html#setup-upgrade

Upgrading Elasticsearchedit

Before upgrading Elasticsearch:

• Consult the breaking changes docs.
• Use the Elasticsearch Migration Plugin to detect potential issues before upgrading.
• Test upgrades in a dev environment before upgrading your production cluster.
• Always back up your data 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:

Upgrade From	Upgrade To	Supported Upgrade Type
1.x	5.x	Reindex to upgrade
2.x	2.y	Rolling upgrade (where y > x)
2.x	5.x	Full cluster restart
5.0.0 pre GA	5.x	Full cluster restart
5.x	5.y	Rolling upgrade (where y > x)

Indices created in Elasticsearch 1.x or before

Elasticsearch is able to read indices created in the previous major version only. For instance, Elasticsearch 5.x can use indices created in Elasticsearch 2.x, but not those created in Elasticsearch 1.x or before.

This condition also applies to indices backed up with snapshot and restore. If an index was originally created in 1.x, it cannot be restored into a 5.x cluster even if the snapshot was made by a 2.x cluster.

Elasticsearch 5.x nodes will fail to start in the presence of too old indices.

See Reindex to upgrade for more information about how to upgrade old indices.