Elasticsearch troubleshooting

Problem Definition

Error too_long_http_line_exception

Failed to load table data: Problem to connect to elasticsearch. too_long_http_line_exception Root causes: too_long_http_line_exception: An HTTP line is larger than 4096 bytes.

cause

This error occurs when an HTTP request line sent to Elasticsearch exceeds the default maximum length (4096 bytes).

Solution

Increase the value of http.max_initial_line_length in your elasticsearch.yml configuration file if your application sends very long HTTP request lines to Elasticsearch.

Real-world scenario:

If your system uses dashboards, queries, or integrations that generate complex requests with many filters, fields, or parameters, the initial HTTP line can easily exceed the default 4096 bytes. For example, some BI tools or custom reporting dashboards may send requests with long query strings, especially when users select many columns or apply multiple filters at once. In such cases, increasing this value (e.g., to 16kb) prevents connection errors and ensures data loads correctly.

Step-by-step fix:

1. Open your Elasticsearch configuration file

• Locate or create the file named elasticsearch.yml in your project directory.

2. Increase the HTTP line length limit

• Add or update the following line [DOCS]:

http.max_initial_line_length: 16kb

or Elasticsearch environment variable could be set in your docker-compose.yml file:

environment:
  - http.max_initial_line_length: "16kb"

• You can adjust 16kb to a value that fits your needs.

3. Update your Docker Compose configuration

   • Make sure your Docker Compose file mounts the updated config:

   - ./elasticsearch.yml:/usr/share/elasticsearch/config/elasticsearch.yml:ro # (optional) Custom config

   • For a full example, see Docker Compose.

4. Restart your Elasticsearch container

   • Run the following command to apply the changes:

   docker compose restart elasticsearch

5. Verify the fix

• Try loading your dashboard or running the query again to confirm the error is resolved.

For more details, see the Elasticsearch Networking Settings documentation.

Reference:

• Elasticsearch Networking Settings