> ## Documentation Index
> Fetch the complete documentation index at: https://docs.kash.bot/llms.txt
> Use this file to discover all available pages before exploring further.

# OUTCOME_INDEX_INVALID

> HTTP 400 — Outcome index invalid

**HTTP status:** 400 · **Title:** "Outcome index invalid"

## When it fires

`outcomeIndex` is greater than or equal to the market's outcome count, or negative.

## Why it happens

* You hard-coded `outcomeIndex: 1` (assuming a binary market) and pointed at a multi-outcome market.
* Off-by-one: the field is **zero-indexed** — first outcome is `0`, not `1`.
* A bug computed the index from a label without bounds-checking.

## How to fix

* Look up the market via `GET /v1/markets/:id` and check `outcomes.length` — valid range is `[0, length - 1]`.
* Map outcome labels to indices once when you fetch the market, then use the index throughout your code.

## Related codes

* [`MARKET_NOT_FOUND`](./MARKET_NOT_FOUND.md), [`MARKET_NOT_TRADEABLE`](./MARKET_NOT_TRADEABLE.md), [`VALIDATION_FAILED`](./VALIDATION_FAILED.md)