OpenRouter / OpenAI API

OpenRouter 401 Unauthorized Error — Fix Authentication Failures

Fix OpenRouter returning 401 Unauthorized despite having a valid API key with credits Includes evidence for OpenRouter troubleshooting demand.

Source-backed Last updated May 13, 2026 2 sources Needs local verification

Category: OpenAI API
Error signature: OpenRouter 401 Unauthorized — Provider returned error
Quick fix: Verify the account session, API key, provider settings, and environment where the failing tool is running.
Updated: May 13, 2026
Verification status: Source-backed
Evidence: 2 public source URLs

Before you change production

This page includes public source URLs in the imported troubleshooting record. Compare those references with your version and environment before applying changes.

Reproduce the smallest failing action and save non-secret logs before changing configuration.
Check versions for OpenRouter, related SDKs, package managers, CI runners, and hosting providers.
Change one setting or dependency at a time, then rerun the same failing command or request.
Avoid destructive commands, credential rotation, billing changes, or security relaxations without a rollback plan.

What this error means

OpenRouter 401 Unauthorized — Provider returned error is a OpenRouter failure pattern reported for developers trying to fix openrouter returning 401 unauthorized despite having a valid api key with credits. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Multiple GitHub issues report OpenRouter returning HTTP 401 despite verified API keys with available credits. Users report the error randomly alternates between 'Provider returned error' and '401 unauthorized'. Direct curl requests work fine, suggesting a malformed request from the client side.

Common causes

Developers using Cline, Hermes Agent, and other AI coding tools with OpenRouter as the provider frequently encounter intermittent 401 errors even after verifying their API key and credit balance. The error appears randomly alongside 'Provider returned error' messages, making it difficult to diagnose whether it's a client-side request formatting issue or an OpenRouter server-side authentication bug.
Multiple GitHub issues report OpenRouter returning HTTP 401 despite verified API keys with available credits. Users report the error randomly alternates between 'Provider returned error' and '401 unauthorized'. Direct curl requests work fine, suggesting a malformed request from the client side.

Quick fixes

Confirm the exact error signature matches OpenRouter 401 Unauthorized — Provider returned error.
Check the OpenRouter account, local tool state, and provider configuration involved in the failing workflow.
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

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

Diagnostic flow for this page

Match OpenRouter 401 Unauthorized — Provider returned error exactly before applying the quick fix.
Compare the failing environment with OpenRouter versions, account scope, provider settings, and deployment context.
Check the listed common causes in order, starting with the cause that best matches your logs.
Use the evidence status below to decide whether to confirm against public sources or official documentation.
Apply one reversible change, rerun the smallest failing action, and keep rollback notes.

FAQ

What does OpenRouter 401 Unauthorized — Provider returned error mean in OpenRouter?

OpenRouter 401 Unauthorized — Provider returned error indicates the workflow described by "OpenRouter 401 Unauthorized Error — Fix Authentication Failures" failed in a OpenAI API context. Start by confirming the exact signature and the component that emitted it.

What should I check first for OpenRouter 401 Unauthorized — Provider returned error?

Check whether this cause matches your environment: Developers using Cline, Hermes Agent, and other AI coding tools with OpenRouter as the provider frequently encounter intermittent 401 errors even after verifying their API key and credit balance. The error appears randomly alongside 'Provider returned error' messages, making it difficult to diagnose whether it's a client-side request formatting issue or an OpenRouter server-side authentication bug.

Is the OpenRouter 401 Unauthorized — Provider returned error guidance source-backed?

The "OpenRouter 401 Unauthorized Error — Fix Authentication Failures" page is labeled source-backed. It has 2 public source URLs from github.com, so use that evidence status when deciding how much additional verification you need.

When should I avoid the quick fix for OpenRouter 401 Unauthorized — Provider returned error?

For "OpenRouter 401 Unauthorized Error — Fix Authentication Failures", avoid applying "Verify the account session, API key, provider settings, and environment where the failing tool is running." when the error text differs, the affected version or provider is different, or the change would touch credentials, billing, DNS, production deploy settings, or irreversible data.

What should I collect before debugging OpenRouter 401 Unauthorized — Provider returned error?

For "OpenRouter 401 Unauthorized Error — Fix Authentication Failures", collect the failing OpenRouter command or request, non-secret configuration, versions, timestamps, request IDs when available, and the smallest reproduction that still triggers the signature.