Why are my retries failing on Anthropic but not OpenAI?

There are a few common reasons retries can “work” with OpenAI but seem to fail with Anthropic, even when your code looks similar:

1) Anthropic may be rejecting the same request repeatedly

If the underlying issue is a bad request (invalid params, schema mismatch, unsupported tool/function setup, etc.), retries won’t help. OpenAI might be more forgiving in some cases, or your OpenAI code path may differ slightly.

Check whether the error is a:

• 4xx → usually not retryable
• 5xx / timeout / rate limit → often retryable

2) Different rate-limit behavior

Anthropic can be stricter about:

• request rate
• token throughput
• burst traffic
• concurrent requests

If you retry too quickly, you may keep hitting the same rate limit. OpenAI may tolerate your traffic pattern better.

What to do:

• use exponential backoff
• add jitter
• respect any Retry-After headers
• reduce concurrency

3) You may be retrying on the wrong exceptions

Some SDKs or wrappers classify errors differently across providers.

Make sure you’re retrying on:

• network errors
• timeouts
• 429s
• 500s / 502s / 503s / 504s

But not on:

• validation errors
• auth errors
• context length errors

4) Anthropic request formatting may be different

If you’re using a shared abstraction, your retry may be replaying a request that Anthropic expects in a different shape:

• message format
• tool call schema
• system prompt placement
• max tokens / model name differences

A subtle mismatch can cause every retry to fail identically.

5) Non-idempotent side effects

If your first attempt partially succeeds and your retry repeats a non-idempotent action, Anthropic may behave differently depending on how your app handles:

• tool invocation
• streaming interruptions
• conversation state mutation

6) SDK differences

Your retry logic may be implemented differently in the two client libraries:

• different default retry counts
• different timeout settings
• different handling of streaming failures

OpenAI’s SDK may automatically retry certain failures that Anthropic’s does not, or vice versa.

---

Best next steps

1. Log the exact error type/code/message from Anthropic.
2. Compare the raw request payload sent to both providers.
3. Confirm whether failures are 4xx vs 5xx/429.
4. Add exponential backoff with jitter.
5. If using streaming, verify your retry logic can safely restart the stream.

If you want, paste:

• the exact Anthropic error
• your retry code
• the request payload

and I can tell you why it’s failing specifically.