Laravel: Auth guard [sanctum] is not defined

# Troubleshooting Laravel Sanctum: Why `Auth guard [sanctum] is not defined` Appears As a senior developer working with Laravel, integrating new authentication systems like Sanctum can sometimes lead to subtle configuration errors, even when following the documentation precisely. The error message you are encountering—`Auth guard [sanctum] is not defined`—is frustrating because it suggests the system doesn't recognize the authentication mechanism you are trying to invoke via middleware. This post will diagnose why this error occurs when setting up Laravel Sanctum for API token authentication and provide the correct, robust solution. ## Understanding Laravel Authentication Guards To understand the issue, we must first look at how Laravel manages authentication guards. The `auth` facade and associated middleware rely entirely on the configuration defined in `config/auth.php`. This file defines which drivers (session, token, database) are available and what guards (like `web`, `api`) map to those drivers. When you use `Route::middleware('auth:guard_name')`, Laravel looks for a guard named `guard_name` within the configuration. If that specific guard is not explicitly defined in the `guards` array of `config/auth.php`, it correctly throws the error: `Auth guard [guard_name] is not defined`. ## The Sanctum Integration Discrepancy In your provided setup, you have correctly configured the API guard to use the token driver: ```php // config/auth.php excerpt 'guards' => [ // ... 'api' => [ 'driver' => 'token', // This is the key piece for Sanctum tokens 'provider' => 'users', 'hash' => false, ], ], ``` However, you are attempting to use the middleware `auth:sanctum`. The core issue here is that Laravel does not automatically create a guard named `sanctum` just because you installed Sanctum. Instead, Sanctum integrates by leveraging one of the existing guards you define, typically the `api` guard you configured for token-based authentication. The `HasApiTokens` trait on your `Client` model correctly tells Sanctum how to handle tokens, but the routing layer needs to call the guard that is actually defined in the configuration file. ## The Solution: Using the Defined API Guard The fix is straightforward: instead of referencing a non-existent guard named `sanctum`, you must reference the guard you explicitly configured for API token handling, which is `'api'`. You need to change your route definition from: `Route::middleware('auth:sanctum')` To: `Route::middleware('auth:api')` By using `auth:api`, you instruct Laravel to use the authentication logic defined for the `api` guard (which utilizes the `token` driver) to validate the incoming request, seamlessly integrating with your Sanctum token setup. ### Corrected Code Example Here is how your `routes/api.php` file should look after applying this correction: ```php get('/dashboard/get_current_client/', [Dashboard::class, 'get_current_client']); Route::get('/dashboard/client_data/', [Dashboard::class, 'client_data']); ``` ## Best Practices for API Security in Laravel This experience highlights a crucial architectural point in building secure APIs with Laravel. When dealing with different authentication methods (session vs. token), always map those methods explicitly to the guards defined in your configuration. Following established patterns ensures that your application remains predictable and adheres to best practices, which is essential when scaling large applications using tools like those found on the [Laravel documentation](https://laravelcompany.com). Remember that Sanctum enhances Laravel’s built-in token functionality; it doesn't replace the core authentication guard system. Always consult the official guides for the most up-to-date methods on implementing features like API tokens and middleware correctly. By switching to `auth:api`, you resolve the undefined guard error, allowing your Sanctum-backed endpoints to function as intended.