Portkey Gateway rewrites service_tier to deprecated Anthropic 'speed' field causing 400 errors

What this error means

Claude API 400 Bad Request — service_tier rewritten to deprecated 'speed' field is a Anthropic API failure pattern reported for developers trying to fix anthropic api 400 error when using service_tier through portkey gateway. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Official Portkey-AI/gateway GitHub issue. Portkey gateway translates OpenAI-style service_tier to Anthropic’s deprecated ‘speed’ field per docs-core #869, but Anthropic’s Messages API no longer accepts ‘speed’ — it uses service_tier natively. Result: any request with service_tier set returns HTTP 400. Priority Tier unreachable through gateway.

Common causes

• Developers using Portkey as an LLM gateway to route requests to the Anthropic API receive HTTP 400 errors because Portkey incorrectly translates OpenAI-style service_tier to Anthropic’s deprecated ‘speed’ field. This makes Priority Tier (fast mode) completely unreachable through the gateway, blocking production workloads that depend on reduced latency.
• Official Portkey-AI/gateway GitHub issue. Portkey gateway translates OpenAI-style service_tier to Anthropic’s deprecated ‘speed’ field per docs-core #869, but Anthropic’s Messages API no longer accepts ‘speed’ — it uses service_tier natively. Result: any request with service_tier set returns HTTP 400. Priority Tier unreachable through gateway.

Quick fixes

1. Confirm the exact error signature matches Claude API 400 Bad Request — service_tier rewritten to deprecated 'speed' field.
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/Portkey-AI/gateway/issues/1645

Evidence note: Official Portkey-AI/gateway GitHub issue. Portkey gateway translates OpenAI-style service_tier to Anthropic’s deprecated ‘speed’ field per docs-core #869, but Anthropic’s Messages API no longer accepts ‘speed’ — it uses service_tier natively. Result: any request with service_tier set returns HTTP 400. Priority Tier unreachable through gateway.

Related errors

• Anthropic API 400 error through proxy
• Portkey gateway Anthropic routing error
• Anthropic service_tier not working with OpenAI SDK

FAQ

What should I check first?

Start with the exact Claude API 400 Bad Request — service_tier rewritten to deprecated 'speed' field 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 Claude API 400 Bad Request — service_tier rewritten to deprecated 'speed' field.