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Claude API error 529? Why it's overloaded and what to do

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Source checked 9 Oct 2026 · Published 23 Oct 2026 · Last reviewed 23 Oct 2026 · By Ctrl+Z Therapy (how we test)

The short answer

Error 529 is overloaded_error: the API is temporarily overloaded. Claude's API docs say 529 errors can occur when the API experiences high traffic across all users. That's different from 429 rate_limit_error, which means your organization has hit a rate limit or a spend cap.

What to do

  1. Retry with exponential backoff. The official SDK automatically retries transient failures, including 5xx server errors, twice by default, honoring the retry-after header when present.
  2. In your app, catch 529 and show a friendly 'busy, try again' message instead of failing.
  3. Ask your AI tool: "Make sure my Claude API calls retry 529 overloaded errors with exponential backoff, and show users an 'AI is busy, try again' message instead of crashing."

Source

Checked on 9 Oct 2026. Prices, limits and settings change, so check the source before you rely on them.

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