laravel Unable to prepare route ... for serialization. Uses Closure

When I clear caches in my Laravel 5.2 project, I see this error message:

[LogicException] Unable to prepare route [panel] for serialization. Uses Closure.

I think that it's related with a route

Route::get('/article/{slug}', 'Front@slug');

associated with a particular method in my controller:

public function slug($slug) {
    $article = Article::where('slug',$slug)->first();

    $id = $article ->id_article ;
    
    if ( ($article=== null) || (is_null($id)) ) return view('errors/Db');

    else return view('detail')->with(array('article'=> $article,  'title'=>'My title - '.$article->title)); 
}`

In short, from a master view I pass $slug, that is a shortlink to the article, with $slug , which is unique in the database, I identify the record and then I pass it's contents to the detail view.

I didn't have any problem when I wrote the method, infact it worked like a charm, but after I cleaned caches, I get that error and the links in the master view don't show any shortcode.

Where am I doing wrong?

> I think that it's related with a route > > Route::get('/article/{slug}', 'Front@slug'); > > associated with a particular method in my controller:

No, thats not it. The error message is coming from the route:cache command, not sure why clearing the cache calls this automatically.

The problem is a route which uses a Closure instead of a controller, which looks something like this:

//                       Thats the Closure
//                             v 
Route::get('/some/route', function() {
    return 'Hello World';
});

Since Closures can not be serialized, you can not cache your routes when you have routes which use closures.

If none of your routes contain closures, but you are still getting this error, please check

> routes/api.php

Laravel has a default auth api route in the above file.

Route::middleware('auth:api')->get('/user', function (Request $request) {
    return $request->user();
});

which can be commented or replaced with a call to controller method if required.

This is definitely a bug.Laravel offers predefined code in routes/api.php

Route::middleware('auth:api')->get('/user', function (Request $request) { 
     return $request->user(); 
});

which is unabled to be processed by:

php artisan route:cache

This definitely should be fixed by Laravel team.(check the link),

simply if you want to fix it you should replace routes\api.php code with some thing like :

Route::middleware('auth:api')->get('/user', 'UserController@AuthRouteAPI');

and in UserController put this method:

 public function AuthRouteAPI(Request $request){
    return $request->user();
 }

The Actual solution of this problem is changing first line in web.php

Just replace Welcome route with following route

Route::view('/', 'welcome');

If still getting same error than you probab

the solustion when we use routes like this:

Route::get('/', function () {
    return view('welcome');
});

laravel call them Closure so you cant optimize routes uses as Closures you must route to controller to use php artisan optimize

Check your routes/web.php and routes/api.php

Laravel comes with default route closure in routes/web.php:

Route::get('/', function () {
    return view('welcome');
});

and routes/api.php

Route::middleware('auth:api')->get('/user', function (Request $request) {
    return $request->user();
});

if you remove that then try again to clear route cache.

If someone is still looking for an answer, for me the problem was in routes/web.php file. Example:

Route::get('/', function () {
    return view('welcome');
});

It is also Route, so yeah...Just remove it if not needed and you are good to go! You should also follow answers provided from above.

If you're coming to this problem because you've upgraded Laravel <5.8 project up to >=5.8, you've likely used the ./vendor/bin/carbon-upgrade method to upgrade the project as suggested by your terminal. In this case, you simply need to remove the following two blocks from the bottom of your composer.json file and composer install again:

    "post-install-cmd": [
        "Illuminate\\Foundation\\ComposerScripts::postInstall",
        "php artisan optimize"
    ],
    "post-update-cmd": [
        "Illuminate\\Foundation\\ComposerScripts::postUpdate",
        "php artisan optimize"
    ],

In order to troubleshoot this (at least in laravel 6): The action property inside Route.php has all the info needed. A better error message should be possible to provide by laravel.

What I did was to add a dd($this->action) just before the exception is thrown here: https://github.com/laravel/framework/blob/6.x/src/Illuminate/Routing/Route.php#L917

With that in place I could easily pinpoint the location, in my case api.php and lines 22-24:

array:6 [
  "middleware" => "api"
  "domain" => "local-api.mydomain.com"
  "uses" => Closure()^ {#6497
    class: "App\Providers\RouteServiceProvider"
    this: App\Providers\RouteServiceProvider {#5743 …}
    file: "./routes/api.php"
    line: "22 to 24"
  }
  "namespace" => "App\Http\Controllers"
  "prefix" => null
  "where" => []
]

check that your web.php file has this extension

use Illuminate\Support\Facades\Route;

my problem gone fixed by this way.