Uncaught ReflectionException: Class App\Http\Kernel does not exist laravel 8 - namespaces

Question

composer.json >>>>
{
"name": "laravel/laravel",
"type": "project",
"description": "The Laravel Framework.",
"keywords": [
"framework",
"laravel"
],
"license": "MIT",
"require": {
"php": "^7.3",
"fideloper/proxy": "^4.2",
"fruitcake/laravel-cors": "^2.0",
"guzzlehttp/guzzle": "^7.0.1",
"laravel/framework": "^8.0",
"laravel/tinker": "^2.0",
"laravel/ui": "^3.0",
"laravelcollective/html": "^6.2",
"spatie/laravel-permission": "^3.17",
"tcg/voyager": "^1.6"
},
"require-dev": {
"facade/ignition": "^2.3.6",
"fzaninotto/faker": "^1.9.1",
"mockery/mockery": "^1.3.1",
"nunomaduro/collision": "^5.0",
"phpunit/phpunit": "^9.3"
},
"config": {
"optimize-autoloader": true,
"preferred-install": "dist",
"sort-packages": true
},
"extra": {
"laravel": {
"dont-discover": []
}
},
"autoload": {
"psr-4": {
"App\\": "app/",
"Database\\Factories\\": "database/factories/",
"Database\\Seeders\\": "database/seeders/"
}
},
"autoload-dev": {
"psr-4": {
"Tests\\": "tests/"
}
},
"minimum-stability": "dev",
"prefer-stable": true,
"scripts": {
"post-autoload-dump": [
"Illuminate\\Foundation\\ComposerScripts::postAutoloadDump",
"#php artisan package:discover --ansi"
],
"post-root-package-install": [
"#php -r \"file_exists('.env') || copy('.env.example', '.env');\""
],
"post-create-project-cmd": [
"#php artisan key:generate --ansi"
]
}
}
this is laravel 8 php 7 and think it could be related to my namespace configuration, because i haven't all understood yet.
hat I have already done :
Delete /vendor and make a new install with composer install
composer dump-autoload
composer update btw, I get the error when I insert the php serve
Please inform me if i should post another file that could be useful.
Here is my composer.json file :
{
"name": "laravel/laravel",
"type": "project",
"description": "The Laravel Framework.",
"keywords": [
"framework",
"laravel"
],
"license": "MIT",
"require": {
"php": "^7.3",
"fideloper/proxy": "^4.2",
"fruitcake/laravel-cors": "^2.0",
"guzzlehttp/guzzle": "^7.0.1",
"laravel/framework": "^8.0",
"laravel/tinker": "^2.0",
"laravel/ui": "^3.0",
"laravelcollective/html": "^6.2",
"spatie/laravel-permission": "^3.17",
"tcg/voyager": "^1.6"
},
"require-dev": {
"facade/ignition": "^2.3.6",
"fzaninotto/faker": "^1.9.1",
"mockery/mockery": "^1.3.1",
"nunomaduro/collision": "^5.0",
"phpunit/phpunit": "^9.3"
},
"config": {
"optimize-autoloader": true,
"preferred-install": "dist",
"sort-packages": true
},
"extra": {
"laravel": {
"dont-discover": []
}
},
"autoload": {
"psr-4": {
"App\\": "app/",
"Database\\Factories\\": "database/factories/",
"Database\\Seeders\\": "database/seeders/"
}
},
"autoload-dev": {
"psr-4": {
"Tests\\": "tests/"
}
},
"minimum-stability": "dev",
"prefer-stable": true,
"scripts": {
"post-autoload-dump": [
"Illuminate\\Foundation\\ComposerScripts::postAutoloadDump",
"#php artisan package:discover --ansi"
],
"post-root-package-install": [
"#php -r \"file_exists('.env') || copy('.env.example', '.env');\""
],
"post-create-project-cmd": [
"#php artisan key:generate --ansi"
]
}
}