# Anthropic API 529: Overloaded Error

TL;DR: Anthropic 529 overloaded_error is normally a provider-side capacity signal. Your request may be valid, but the service cannot process it right now.

Target query: Anthropic API 529 overloaded
Likely fault area: provider/server side
Run diagnosis: https://llmping.app/#diagnose

## What this error means

Anthropic API 529 means the provider is overloaded or temporarily unable to serve your request at normal capacity.

## Is it code, key, rate limit, or server-side?

Category: provider_overload
Likely fault area: provider/server side

## Immediate checklist

- Confirm whether the response type is overloaded_error.
- Retry with exponential backoff and a low max retry count.
- Check whether only one model is affected or all Anthropic models are affected.
- Use a fallback provider or queue non-interactive jobs until the overload clears.

## cURL test command

```bash
curl https://api.anthropic.com/v1/messages \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "content-type: application/json" \
  -d '{"model":"claude-3-5-haiku-latest","max_tokens":16,"messages":[{"role":"user","content":"ping"}]}'
```

## Common fixes

- Do not treat 529 as a bad API key. It is usually not an auth problem.
- Add backoff, jitter, circuit breaking, and a fallback route for production workloads.
- Lower max_tokens for interactive retries so the fallback path returns quickly.
- Move batch work to a queue and retry later instead of blocking user requests.

## Related errors

- https://llmping.app/errors/claude/econnreset/
- https://llmping.app/status/anthropic/
- https://llmping.app/errors/openai/429/