Script @php artisan package:discover handling the post-autoload-dump event returned with error code 255

I moved my project from desk to another.
When I run php artisan it does not work.

I tried to run composer update, but it returns the error

> Script @php artisan package:discover handling the post-autoload-dump event returned with error code 255

This is how I solved this after an upgrade from laravel version 6.x - 7.x:

In App\Exceptions\Handler changed

//Use Exception;
Use Throwable;

Then methods to accept instances of Throwable instead of Exceptions as follows:

//public function report(Exception$exception);
public function report(Throwable $exception);
    
//public function render($request, Exception $exception);
public function render($request, Throwable $exception);

In config\session.php:

//'secure' => env('SESSION_SECURE_COOKIE', false),
'secure' => env('SESSION_SECURE_COOKIE', null),

Then run composer update

I solved the problem this way:

cd bootstrap/cache/
rm -rf *.php

The bootstrap directory contains the app.php file that initializes the structure. This directory also houses a cache directory that contains structure-generated files for performance optimization, such as files and route cache services. Laravel stores configuration files, provider, and cached services to optimize the fetching of this information. The problem with me was when the other developer ran the 'php artisan config: cache' command on your machine and since the cache folder contains files that can be deleted, I deleted them and solved the problem.

If this happened after Laravel update from 6.x to 7.x, then this could be due to the update of Symfony. See the upgrade guide of this part: https://laravel.com/docs/7.x/upgrade#symfony-5-related-upgrades

I was upgrading my Laravel from 5.8 to 8.0 and I got this error.

So my fixes were

1. As @nobuhiroharada mentioned that I had missed .env file in my project

2. Second is that Laravel removed Exception and replaced it with Throwable. So we need to fix that in our app\Exceptions\Handler.php. One can refer Medium.com for the error fix.

3. In the upgrade guide of Laravel 8.x you need to update the dependencies like this

4. Next, in your composer.json file, remove classmap block from the autoload section and add the new namespaced class directory mappings:

"autoload": {
    "psr-4": {
        "App\\": "app/",
        "Database\\Factories\\": "database/factories/",
        "Database\\Seeders\\": "database/seeders/"
    }
},

5. Finally from bootstrap\cache delete the cache files and run composer update.

These 5 steps might help you remove the error you are facing in your Laravel Project.

This happens because you have upgraded to Laravel 7.

To fix it, update app/Exceptions/Handler.php like so:

<?php

namespace App\Exceptions;

use Illuminate\Foundation\Exceptions\Handler as ExceptionHandler;
use Throwable; // <-- ADD THIS

class Handler extends ExceptionHandler
{
    public function report(Throwable $exception) // <-- USE Throwable HERE
    {
        parent::report($exception);
    }
    public function render($request, Throwable $exception) // AND HERE
    {
        return parent::render($request, $exception);
    }
}

This is documented in the official upgrade guide here:

https://laravel.com/docs/7.x/upgrade#symfony-5-related-upgrades

I got the same problem in Win 8 and solve it:

Here is the steps.

Step-1: Go to your project directory

Step-2: And type command cd bootstrap/cache/

Step-3: Again type command del -rf *.php

Step-4: Update your composer composer update

Step-5: Now you are done: php artisan serve

Thanks.

Do you have .env file in your new project?

I had same error message. When I add .env file, error is gone.

success message like this.

Generating optimized autoload files
> Illuminate\Foundation\ComposerScripts::postAutoloadDump
> @php artisan package:discover
Discovered Package: fideloper/proxy
Discovered Package: ixudra/curl
Discovered Package: laravel/tinker
Discovered Package: nesbot/carbon
Discovered Package: socialiteproviders/manager
Package manifest generated successfully.

I hope this will help you.

maybe you have an error in the project code (for example, in routes or controller). This may be one of the reasons for this error.

In my project, the web.php file has a syntax error. I defined this when I started the php artisan command

C:\OSPanel\domains\lara.shop.loc>php artisan
In web.php line 
  syntax error, unexpected end of file  

Same issue when I update laravel from 6.x to 7.x

I tried the most voted answer but it didn't work, then I used php artisan serve I noticed that:

RuntimeException

In order to use the Auth::routes() method, please install the laravel/ui package.

Try composer require laravel/ui maybe it will work.

I solve this error by deleting the vendor table then run composer update. I'm using Laravel 7. So, if you are not updating from the older Laravel version, maybe this is the solution.

I had this same problem when running composer update in a Laravel project. In the package.json it's configured to run artisan package:discover, which failed with:

Class 'Symfony\Component\Translation\Translator' not found in vendor/nesbot/carbon/src/Carbon/Translator.php on line 18

When I looked in the vendor/symfony/translation directory I found that it was completely empty, which explained the error.

The solution was to completely delete the vendor directory and then re-run composer update. This was the only way that I was able to make composer install the missing files.

I deleted composer.lock file and ran composer update.

That solved mine

This is not an actual error. If you look a bit above you'll see the actual error. In my case, there was an error in my code:

PHP Fatal error:  Declaration of 
App\Exceptions\Handler::render($request, App\Exceptions\Exception $exception)
must be compatible with 
Illuminate\Foundation\Exceptions\Handler::render($request, Throwable $e)

It is not possible to tell you what is actually a problem in your code, so you have to look real reason for this error in your stack trace.

nothing worked. So I installed a new project, and I read Handler.php in App\Exceptions, it was different, probably because I copied some solution and Internet and deleted the following:

protected $dontReport = [
    //
];

protected $dontFlash = [
    'password',
    'password_confirmation',
];

I copy here all of Handler.php generated by laravel 7.5, may be useful for someone:

<?php

namespace App\Exceptions;

use Illuminate\Foundation\Exceptions\Handler as ExceptionHandler;
use Throwable;

class Handler extends ExceptionHandler
{
    /**
     * A list of the exception types that are not reported.
     *
     * @var array
     */
    protected $dontReport = [
        //
    ];

/**
 * A list of the inputs that are never flashed for validation exceptions.
 *
 * @var array
 */
protected $dontFlash = [
    'password',
    'password_confirmation',
];

/**
 * Report or log an exception.
 *
 * @param  \Throwable  $exception
 * @return void
 *
 * @throws \Exception
 */
public function report(Throwable $exception)
{
    parent::report($exception);
}

/**
 * Render an exception into an HTTP response.
 *
 * @param  \Illuminate\Http\Request  $request
 * @param  \Throwable  $exception
 * @return \Symfony\Component\HttpFoundation\Response
 *
 * @throws \Throwable
 */
public function render($request, Throwable $exception)
{
    return parent::render($request, $exception);
}

}

Hello everybody/ hello world. I solved my problem that way:

---

I deleted my project I created a new folder and cloned the repository again and after that I gave composer install / update

good luck.

In my case there is missing folder and its file Kernel.php in

> app/Console

So I created app/Console/Kernel.php using code from previous project. Now everything working fine.

Make sure your config\constants.php (and/or resources\lang\en\local.php) has no syntax errors. I get this error a lot by missing commas in constants.php file.

I had the same issue, my problem was the PHP version of the server account did not match my Docker container. The SSH terminal was using the global php version for the server.

php -v

Confirm it's the version your project needs.

---

Composer did warn me that a higher php version was required but I rm -rf'd /vendor and ./composer.lock without paying too much attention to the warnings!

I got the same problem in Win 10 and solve it:

Here is the steps.

Step-1: Go to your project directory

Step-2: Update your composer

> composer update

Step-3: Now you are done: php artisan serve

Thanks.

Getting this error when my composer version 2.x then i rollback this

composer self-update --1

Now its perfectly working