Anthropic 529 overloaded_error: this means try again, with backoff, not a bug in your code

TL;DR

For "overloadederror": check the error type in the response body. overloaded\error is capacity, not validation: your request was fine, the servers were full. Do not "fix" the payload.

overloaded_error

Steps

1. Check the error type in the response body. overloaded_error is capacity, not validation: your request was fine, the servers were full. In a stream this arrives as an SSE error event, not as an HTTP status, so code that only checks the status code misses it.
2. Retry with exponential backoff and jitter. The official SDKs already do this twice by default and honor the retry-after header when one is present; raise max_retries if you need more attempts.
3. If you wrote your own HTTP client, implement the same: honor retry-after, otherwise wait roughly 1s, 2s, 4s with jitter before giving up.
4. For streams, treat an error event the same as a 529: abort that attempt and retry the request fresh.
5. Do not "fix" the payload. Changing the prompt in response to a 529 just burns tokens.

When to use

You are seeing this: A request fails with HTTP 529 and error type overloaded\error. Use this skill when you run into "Anthropic 529 overloadederror: this means try again, with backoff, not a bug in your code".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Why this happens

Check the error type in the response body. overloaded\_error is capacity, not validation: your request was fine, the servers were full.

A 529 overloaded_error is documented as temporary overload, with SDKs retrying twice by default and honoring retry-after. Mid-stream errors arrive as SSE error events after a 200. Verified live at https://docs.anthropic.com/en/api/errors and https://docs.anthropic.com/en/api/messages-streaming.