Please follow the below steps to upgrade the Laravel version in your exiting project.

• PHP 7.3.0 Required

  Likelihood Of Impact: Medium

  The new minimum PHP version is now 7.3.0.

• Updating Dependencies

  The following first-party packages have new major releases to support Laravel 8. If there are any, read through their individual upgrade guides before upgrading:

              
  Horizon v5.0
  Passport v10.0
  Socialite v5.0
  Telescope v4.0
              
            

  Finally, examine any other third-party packages consumed by your application and verify you are using the proper version for Laravel 8 support.

  You must have to update below mention packages in composer.json file.

              
  "require": {
    "php": "^7.4.11",
    "fideloper/proxy": "^4.2",
    "fruitcake/laravel-cors": "^1.0",
    "guzzlehttp/guzzle": "^7.0.1",
    "laravel/framework": "^8.0",
    "laravel/passport": "^10.0",
    "laravel/tinker": "^2.0",
    "spatie/laravel-permission": "^3.8",
    "laravel/ui": "^3.0"
  },
  "require-dev": {
    "facade/ignition": "^2.3.6",
    "beyondcode/laravel-dump-server": "^1.0",
    "filp/whoops": "^2.0",
    "fzaninotto/faker": "^1.9.1",
    "mockery/mockery": "^1.3.1",
    "nunomaduro/collision": "^5.0",
    "phpunit/phpunit": "^9.0"
  },
              
            

• In addition, the Laravel installer has been updated to support composer create-project and Laravel Jetstream. Any installer older than 4.0 will cease to work after October 2020. You should upgrade your global installer to ^4.0 as soon as possible.

  Authentication

  All authentication scaffolding has been moved to the laravel/ui repository. If you are using Laravel's authentication scaffolding, you should install the ^3.0 release of this package and the package should be installed in all environments. If you were previously including this package in the require-dev portion of your application's composer.json file, you should move it to the require section:

            
              composer require laravel/ui "^3.0"
            
          

• Now run the below command to upgrade.

            
              composer update
            
          

• After successfully executing of composer update command check the Laravel version

            
              php artisan --version
            
          

• After successfully updated Laravel version. Run below command to serve your project.

            
php artisan key: generate
npm install or yarn
npm run dev or yarn dev
php artisan serve