> ## 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.

# IDEMPOTENCY_KEY_TOO_LONG

> HTTP 400 — Idempotency key too long

**HTTP status:** 400 · **Title:** "Idempotency key too long"

## When it fires

`Idempotency-Key` header value exceeds the 128-character cap.

## Why it happens

* You concatenated several identifiers into the key (user id + market id + timestamp + nonce) and the result blew past 128 chars.
* A library generated an unusually long token (e.g., a JWT instead of a UUID).

## How to fix

* Use a UUID v4 (`uuidgen`, `crypto.randomUUID()`) or a ULID — both are 26–36 chars and unique enough.
* If you need to embed semantic information, hash it: `sha256(your-blob).slice(0, 32)` instead of the raw concatenation.
* Acceptable character set: `[A-Za-z0-9_\-:.]` — see [`IDEMPOTENCY_KEY_FORMAT_INVALID`](./IDEMPOTENCY_KEY_FORMAT_INVALID.md).

## Related codes

* [`IDEMPOTENCY_KEY_FORMAT_INVALID`](./IDEMPOTENCY_KEY_FORMAT_INVALID.md) — disallowed characters
* [`IDEMPOTENCY_KEY_CONFLICT`](./IDEMPOTENCY_KEY_CONFLICT.md) — same key, different body