Fix Elasticsearch “No handler for type [keyword]”

When Elasticsearch reports No handler for type [keyword] declared on field, first check the server version. Elasticsearch 2.x and earlier do not recognize keyword; Elasticsearch 5 introduced it alongside text.

Run this request in a client connected to the affected cluster:

GET /

Read version.number in the response. Confirm the endpoint is the same one used by the failing application or shipper, especially when several environments share similar names.

Match the mapping to the server

For an Elasticsearch 2.x maintenance task, a complete index-creation example includes the old mapping type wrapper:

PUT legacy-hosts
{
  "mappings": {
    "host": {
      "properties": {
        "hostname": { "type": "string", "index": "not_analyzed" }
      }
    }
  }
}

This is historical syntax, not a configuration to copy into a current cluster. On modern Elasticsearch, use a typeless mapping with hostname mapped as keyword.

Prefer a planned upgrade over a permanent workaround

Elasticsearch 2.x is obsolete. Follow a supported migration path, including client and index compatibility checks; a direct jump from an old major release is not automatically supported. Changing a template does not rewrite existing field types. Where the mapping needs to change, create the destination index correctly and reindex the data.

If a recent server produces a similar error for another type, check spelling, plugin requirements, and the exact request structure instead of assuming an old version is the cause.

Check the component installing the mapping

Filebeat and Logstash may install templates automatically. Their versions and templates must be compatible with the server. Disabling automatic template installation only prevents that installation attempt; it does not make an incompatible client or data model compatible.

For full-text search plus exact matching on modern releases, map a field as text with a keyword subfield. Elastic explains the string-type transition and the Elasticsearch 2.4 mapping structure.