Elasticsearch: No Handler for Type [Keyword] Declared on Field [Hostname]

The error No Handler for Type [Keyword] Declared on Field [Hostname] in Elasticsearch usually indicates that there's an issue with the mapping type for the field Hostname. This error often occurs when trying to use a type or field definition that Elasticsearch doesn't recognize or support.

Here’s how to troubleshoot and resolve this issue:

1. Check Elasticsearch Version Compatibility:
   • Make sure you're using the correct field type for your Elasticsearch version. Field types can change between versions. For example, in Elasticsearch 5.x and above, keyword is used for non-analyzed fields, while in earlier versions, string with index set to not_analyzed was used.

2. Verify Your Mapping:

   • Confirm that your index mapping correctly defines the field Hostname with the keyword type. You can check your mapping with the following command:

      

     Copied!

     GET /your_index/_mapping
     

     Replace your_index with the name of your index. Look for the definition of the Hostname field and ensure it’s defined as keyword if that's what you intended.

3. Correct Mapping Definition:

   • If you need to create or update the mapping, you might want to use a correct mapping definition. For example, if you’re using Elasticsearch 7.x or later, your mapping for a keyword field should look like this:

      

     Copied!

     PUT /your_index
     {
       "mappings": {
         "properties": {
           "Hostname": {
             "type": "keyword"
           }
         }
       }
     }
     

4. Reindexing:

   • If you’re working with existing indices and have changed the mapping, you might need to reindex your data to apply the new mapping. This involves creating a new index with the correct mapping and then copying the data from the old index to the new one.

5. Check for Deprecated or Unsupported Features:

   • Ensure that the feature or type you’re trying to use is supported in your Elasticsearch version. For example, keyword fields should be supported in modern versions, but there may be issues if using deprecated features or older configurations.

6. Review Your Data Ingestion:

   • Verify that the data you’re sending to Elasticsearch matches the expected type. If your data is being indexed incorrectly, it might cause type conflicts.

Got an article suggestion? Let us know

Explore more

Elasticsearch Filebeat

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.