OpenRouter / Cloud Platforms

OpenRouter provider returns 401 unauthorized error in Cline and other AI tools

Fix OpenRouter 401 authentication error when using Cline, Aider, or other AI coding tools Includes evidence for OpenRouter troubleshooting demand.

Source-backed Last updated May 11, 2026 2 sources Needs local verification

Category: Cloud Platforms
Error signature: Provider returned error
Quick fix: Verify the account session, API key, provider settings, and environment where the failing tool is running.
Updated: May 11, 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

Provider returned error is a OpenRouter failure pattern reported for developers trying to fix openrouter 401 authentication error when using cline, aider, or other ai coding tools. 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 401 unauthorized despite valid API keys with credits. Cline issue #813 shows users creating 'a dozen API keys' with no success. Aider #853 reports no API activity in dashboard after upgrade.

Common causes

OpenRouter is a major paid AI API gateway. Users report intermittent 401 errors despite valid API keys with credits. Error appears across multiple tools (Cline, Aider, Home Assistant), indicating a broader API-level issue. High commercial value.
Multiple GitHub issues report OpenRouter returning 401 unauthorized despite valid API keys with credits. Cline issue #813 shows users creating 'a dozen API keys' with no success. Aider #853 reports no API activity in dashboard after upgrade.

Quick fixes

Confirm the exact error signature matches 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 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 Provider returned error mean in OpenRouter?

Provider returned error indicates the workflow described by "OpenRouter provider returns 401 unauthorized error in Cline and other AI tools" failed in a Cloud Platforms context. Start by confirming the exact signature and the component that emitted it.

What should I check first for Provider returned error?

Check whether this cause matches your environment: OpenRouter is a major paid AI API gateway. Users report intermittent 401 errors despite valid API keys with credits. Error appears across multiple tools (Cline, Aider, Home Assistant), indicating a broader API-level issue. High commercial value.

Is the Provider returned error guidance source-backed?

The "OpenRouter provider returns 401 unauthorized error in Cline and other AI tools" 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 Provider returned error?

For "OpenRouter provider returns 401 unauthorized error in Cline and other AI tools", 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 Provider returned error?

For "OpenRouter provider returns 401 unauthorized error in Cline and other AI tools", 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.