Debug HTTP 429 Rate Limit Errors

A 429 response means the request was understood but rate limited. The fastest fix is to inspect headers, reduce concurrency and prove the behavior with a minimal request.

Workflow

  1. Capture the exact request method, URL, headers and response status.
  2. Check Retry-After, rate-limit headers and any vendor-specific error body.
  3. Reproduce the request with cURL using placeholder credentials.
  4. Reduce concurrency, add backoff and remove retry loops that multiply traffic.
  5. Review server or provider logs for account, IP, token or endpoint-specific limits.

Checks before production

  • Do not retry immediately in a tight loop after 429.
  • Separate client-side concurrency bugs from provider account limits.
  • Watch background jobs and AI agents that may generate hidden request bursts.
  • Keep 429 handling visible in logs so future spikes are diagnosable.

FAQ

Is 429 always a server bug?

No. It often means client traffic exceeded a configured or provider-side limit.

What should retries do?

Respect Retry-After when present and use exponential backoff with jitter.

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Last updated: May 18, 2026