How to fix Laravel's Route [login] not defined

If you build your projects with Filament, you have probably hit this error when a user's session ends, or when you reinstall the database while you still have a session open:

Route [login] not defined.

It shows up without Filament too, as soon as you have built your own authentication page and named the route something other than exactly login — admin.login, for instance.

Why it happens

Laravel's authentication middleware needs somewhere to send a visitor who is not signed in. By default it assumes a route named login exists, and when it cannot find one it throws instead of redirecting.

The fix

On Laravel 11 and later you override that behaviour from bootstrap/app.php:

<?php

use Illuminate\Foundation\Application;
use Illuminate\Foundation\Configuration\Exceptions;
use Illuminate\Foundation\Configuration\Middleware;

return Application::configure(basePath: dirname(__DIR__))
    ->withRouting(
        web: __DIR__.'/../routes/web.php',
        commands: __DIR__.'/../routes/console.php',
        health: '/up',
    )
    ->withMiddleware(function (Middleware $middleware): void {
        $middleware->redirectGuestsTo('login');
    })
    ->withExceptions(function (Exceptions $exceptions): void {
        //
    })->create();

The whole change is the one call inside the withMiddleware callback:

$middleware->redirectGuestsTo('login');

The argument is just the path you want guests sent to. If your Filament panel lives at /admin, that would be admin/login.

It also accepts a closure, which is what you want when the destination depends on the request:

$middleware->redirectGuestsTo(fn () => route('admin.login'));

With that in place, a visitor without a session lands on your sign-in screen instead of an error page.