Upgrading from Laravel 8 to 9

{
  "require": {
    "php": "^8.0.2",
    "laravel/framework": "^9.0",
    "spatie/laravel-ignition": "^1.0"
  },
  "require-dev": {
    "nunomaduro/collision": "^6.1"
  }
}

composer update

# Only add when using Mailgun
composer require symfony/mailgun-mailer symfony/http-client

# For Postmark, remove the SwiftMailer package and replace
composer remove wildbit/swiftmailer-postmark
composer require symfony/postmark-mailer symfony/http-client

// Laravel 8.x: SwiftMailer-based
$this->withSwiftMessage(function ($message) {
    $message->getHeaders()->addTextHeader('Custom-Header', 'Header Value');
});

// Laravel 9.x: Symfony Mailer-based
use Symfony\Component\Mime\Email;

$this->withSymfonyMessage(function (Email $message) {
    $message->getHeaders()->addTextHeader('Custom-Header', 'Header Value');
});

return [
    'mailers' => [
        'smtp' => [
            // Laravel 8.x settings
            'stream' => [
                'ssl' => [
                    'verify_peer' => false,
                ],
            ],

            // Laravel 9.x settings
            'verify_peer' => false,
        ],
    ],
];

# Amazon S3 driver
composer require -W league/flysystem-aws-s3-v3 "^3.0"

# FTP driver
composer require league/flysystem-ftp "^3.0"

# SFTP driver
composer require league/flysystem-sftp-v3 "^3.0"

return [
    'disks' => [
        'public' => [
            'driver' => 'local',
            // Enable only if you want exceptions on write failures
            'throw' => true,
        ],
    ],
];

// Search and update by name on the related model's table
$user->roles()->updateOrCreate([
    'name' => 'Administrator',
]);

// Merge created_by only on new creation
$user->roles()->firstOrCreate([
    'name' => 'Administrator',
], [
    'created_by' => $user->id,
]);

public function set($model, $key, $value, $attributes)
{
    // In Laravel 9, null may be passed
    if ($value === null) {
        return [
            'address_line_one' => null,
            'address_line_two' => null,
        ];
    }

    if (! $value instanceof AddressModel) {
        throw new InvalidArgumentException('An AddressModel must be provided.');
    }

    return [
        'address_line_one' => $value->lineOne,
        'address_line_two' => $value->lineTwo,
    ];
}

use Illuminate\Support\Facades\Http;

// Extend the timeout for long-running API calls individually
$response = Http::timeout(120)->get('https://example.com/api/status');

// Match return types when overriding core classes
public function offsetGet($key): mixed
{
    return parent::offsetGet($key);
}

return [
    'pgsql' => [
        // Laravel 8.x
        'schema' => 'public',

        // Laravel 9.x
        'search_path' => 'public',
    ],
];

// Before
$this->assertDeleted($user);

// After
$this->assertModelMissing($user);

// Use langPath() to determine the publish destination instead of a fixed path
$this->publishes([
    __DIR__.'/../lang' => app()->langPath('vendor/package-name'),
]);

// Before
'password' => ['required', 'password'],

// After
'password' => ['required', 'current_password'],

$collection->when(function ($collection) {
    // The returned value is what's used as the condition
    return false;
}, function ($collection) {
    // Not executed because false was returned
    $collection->merge([1, 2, 3]);
});

use Illuminate\Support\Facades\Validator;

public function boot()
{
    // Enable only if you need Laravel 8 behavior
    Validator::includeUnvalidatedArrayKeys();
}