Anthropic SDK raises ValueError instead of APIStatusError on Bedrock SSE error events

What this error means

ValueError: Bad response code, expected 200: {'status_code': 400, ':exception-type': 'internalServerException'} is a Anthropic API failure pattern reported for developers trying to handle bedrock streaming errors gracefully in anthropic sdk. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Bedrock SSE stream produces error events with status_code 400 and internalServerException. SDK _stream_decoder.py line 58 raises ValueError instead of propagating to APIStatusError. Developers cannot implement proper error handling or retries.

Common causes

• When Bedrock returns error SSE events during streaming, the SDK raises a raw ValueError instead of a user-friendly APIStatusError. Developers cannot catch specific error types, making retry logic impossible. Affects all Bedrock streaming users.
• Bedrock SSE stream produces error events with status_code 400 and internalServerException. SDK _stream_decoder.py line 58 raises ValueError instead of propagating to APIStatusError. Developers cannot implement proper error handling or retries.

Quick fixes

1. Confirm the exact error signature matches ValueError: Bad response code, expected 200: {'status_code': 400, ':exception-type': 'internalServerException'}.
2. Check the Anthropic API account, local tool state, and provider configuration involved in the failing workflow.
3. Compare the failing environment with a known working setup, then change one configuration value at a time.

Platform/tool-specific checks

• Verify the command, editor, extension, or API client that produced the error.
• Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
• Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

1. Capture the exact error message and the command, editor action, or request that triggered it.
2. Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
3. Review the source evidence below and compare it with your environment.
4. Apply one change at a time and rerun the smallest failing action.
5. Keep the working fix documented for the team or deployment environment.

How to prevent it

• Keep provider/tool configuration documented.
• Record non-secret diagnostics such as tool version, provider name, model name, and command path.
• Add a lightweight check before CI or production workflows depend on the tool.

Sources checked

• https://github.com/anthropics/anthropic-sdk-python/issues/1477

Evidence note: Bedrock SSE stream produces error events with status_code 400 and internalServerException. SDK _stream_decoder.py line 58 raises ValueError instead of propagating to APIStatusError. Developers cannot implement proper error handling or retries.

Related errors

• Anthropic SDK Bedrock AttributeError NoneType streaming
• Bedrock internalServerException retry logic

FAQ

What should I check first?

Start with the exact ValueError: Bad response code, expected 200: {'status_code': 400, ':exception-type': 'internalServerException'} text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed Anthropic API workflow until the root cause is understood.

Is this guaranteed to have one fix?

No. The imported evidence supports the troubleshooting path above, but tool behavior can vary by account, plan, version, provider, and local configuration.

How do I know the fix worked?

Rerun the same command, editor action, or request. The fix is working when that action completes without ValueError: Bad response code, expected 200: {'status_code': 400, ':exception-type': 'internalServerException'}.