Laravel fails when set to production

The error:

Cannot access offset of type Closure in isset or empty at /vendor/laravel/framework/src/Illuminate/Routing/MiddlewareNameResolver.php:61

suggests that Laravel is expecting a middleware name (string), but is instead encountering a Closure (anonymous function) in your middleware configuration.

Why does it only happen in production?

• In local environment, Laravel is more forgiving and may handle certain misconfigurations differently, or you may have different cache states.
• In production or staging, Laravel often uses cached configurations and routes, which can expose issues not seen in development.

Common Causes:

1. Middleware Registered as Closure

   • In app/Http/Kernel.php, middleware should be registered as class names (strings), not as Closures.
   • Example of incorrect usage:

     protected $routeMiddleware = [
         'custom' => function ($request, $next) {
             // ...
         },
     ];
     

   • Correct usage:

     protected $routeMiddleware = [
         'custom' => \App\Http\Middleware\CustomMiddleware::class,
     ];
     

2. Cached Config/Routes

   • If you cached your config or routes while the middleware was misconfigured, the error will persist even after you fix the code.

How to Fix:

1. Check your app/Http/Kernel.php

   • Ensure all middleware are registered as class names, not as Closures.

2. Clear and Rebuild Caches

   php artisan config:clear
   php artisan route:clear
   php artisan cache:clear
   php artisan config:cache
   php artisan route:cache
   

3. Check for Environment-Specific Middleware

   • Make sure you don’t have environment-specific logic that registers middleware differently in production.

Summary:

• Replace any Closure-based middleware with proper class-based middleware.
• Clear and rebuild your caches.

Example Fix:

Suppose you had this in Kernel.php:

protected $routeMiddleware = [
    'my-middleware' => function ($request, $next) {
        // some logic
        return $next($request);
    },
];

Change it to:

protected $routeMiddleware = [
    'my-middleware' => \App\Http\Middleware\MyMiddleware::class,
];

And create the middleware class with:

php artisan make:middleware MyMiddleware

After making these changes, clear your caches as shown above.

Let me know if you need help locating the problematic middleware!