OpenRouter returns 401 Missing Authentication header in OpenClaw and LiteLLM chains

What this error means

401 Missing Authentication header is a OpenRouter failure pattern reported for developers trying to fix openrouter 401 missing authentication header error in proxy chains. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

GitHub issue #51056 shows OpenRouter returning ‘401 Missing Authentication header’ in a proxy chain (openclaw -> openrouter). Error occurs during auth step taking 694ms, with any openrouter model affected.

Common causes

• Occurs specifically in proxy routing chains (e.g., openclaw -> openrouter). The error indicates the authentication header is being dropped during routing — a common but hard-to-debug issue for developers using multi-provider setups.
• GitHub issue #51056 shows OpenRouter returning ‘401 Missing Authentication header’ in a proxy chain (openclaw -> openrouter). Error occurs during auth step taking 694ms, with any openrouter model affected.

Quick fixes

1. Confirm the exact error signature matches 401 Missing Authentication header.
2. Check the OpenRouter account, local tool state, and provider configuration involved in the failing workflow.
3. Verify the account session, API key, provider settings, and environment where the failing tool is running.

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/openclaw/openclaw/issues/51056

Evidence note: GitHub issue #51056 shows OpenRouter returning ‘401 Missing Authentication header’ in a proxy chain (openclaw -> openrouter). Error occurs during auth step taking 694ms, with any openrouter model affected.

Related errors

• OpenRouter proxy authentication error
• LiteLLM OpenRouter 401
• API header dropped in proxy chain

FAQ

What should I check first?

Start with the exact 401 Missing Authentication header text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed OpenRouter 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 401 Missing Authentication header.