Error log: “unknown key [X] for create index” / “unknown parameter [Y]”

Error log: You’ll see this error when trying to create an index, define a mapping, or run a query with an invalid or misspelled parameter.

When creating an index:

JSON

None
{

  "error": {

    "root_cause": [

      {

        "type": "illegal_argument_exception",

        "reason": "unknown key [propertis] for create index" // <-- Typo!

      }

    ],

    "type": "illegal_argument_exception",

    "reason": "unknown key [propertis] for create index"

  },

  "status": 400

}

When running a query:

JSON

None
"root_cause": [

  {

    "type": "parsing_exception",

    "reason": "unknown parameter [fromm]

               did you mean [from]?", // <-- Helpful suggestion!

    "line": 1, "col": 20

  }

]

Why… is this happening? This is a straightforward typo or syntax error. The JSON key or parameter you’ve used in your API request is not recognized by OpenSearch for that specific context.

• In the first example, the user wrote "propertis" inside their _mappings block, but the correct key is "properties".
• In the second example, the user wrote "fromm": 10 in their search query, but the correct parameter is "from": 10.

OpenSearch’s parser is strict. If it doesn’t recognize a key, it rejects the entire request to prevent unexpected behavior. The good news is that the error message is usually very specific and often even suggests the correct spelling.

Best Practice:

1. Read the error message: This is the easiest error to fix. The error message tells you the exact key it doesn’t understand.
2. Check the “did you mean…” suggestion: OpenSearch is often smart enough to guess what you meant. If it provides a suggestion, it’s almost certainly correct.
3. Use OpenSearch dashboards dev tools: The Dev Tools console has excellent auto-complete. As you start typing "prop...", it will suggest "properties", helping you avoid these typos in the first place.
4. Consult the documentation: When in doubt, check the official OpenSearch documentation for the specific API you’re using (e.g., the _search API or _mappings API) to see the full list of valid parameters and keys.

What else can I do? We’ve all been there—staring at a JSON object and unable to see the typo. If you’re stuck, paste your JSON and the error into the OpenSearch community forums. A fresh set of eyes will usually spot the mistake in seconds. For direct support, contact us in The OpenSearch Slack Channel in #General.