Yarn Berry scope-based authentication and expired token error reporting

Yarn Berry does not provide a native configuration option to force distinct error reporting for expired credentials, nor does it support pre-validating environment-variable tokens before initiating the dependency resolution process.

Current Behavior and Limitations

When using npmScopes in .yarnrc.yml, Yarn attaches the mapped token to the Authorization header during the HTTP fetch phase. Because token validation happens lazily—only when a request is made to the registry—Yarn cannot pre-verify the token's status during the initial configuration load.

Regarding error reporting, Yarn surfaces HTTP status codes returned by the registry, but it does not categorize 401 (Unauthorized) or 403 (Forbidden) responses as a specific "Expired Token" error class. These are typically reported as generic fetch failures, which can make it difficult to distinguish between a network timeout, a malformed request, or an expired credential without further investigation.

Recommended Verification Workflow

To identify if a failure is specifically due to an expired token, you must inspect the raw HTTP response codes. Use the following approach:

1. Enable Verbose Logging: Run the installation with the verbose flag to surface the underlying HTTP status codes.

   yarn install --verbose

2. Inspect the Output: Search the logs for the registry URL associated with your scope. Look for 401 Unauthorized or 403 Forbidden responses.
3. Manual Validation: If the logs are ambiguous, verify the token independently using curl to isolate the registry's response from the Yarn client:

   curl -H "Authorization: Bearer YOUR_TOKEN" https://your-registry.com/api/v1/user

Assumptions and Uncertainty

This behavior is based on the standard Yarn Berry (v2+) architecture. We assume the use of standard HTTP-based registries. If you are using a custom Yarn plugin for authentication, the error handling may differ. Additionally, some private registries return non-standard error bodies that may still appear as generic failures even in verbose mode.

Diagnostic Detail Request: Are you using a standard registry (e.g., npmjs, GitHub Packages) or a proprietary internal registry? This determines whether the registry provides a descriptive error body that Yarn might be suppressing.