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

Question

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

Answer 1

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.