diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index cd83ec5e..2d0533e9 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -10,10 +10,10 @@ jobs:
         strategy:
             fail-fast: false
             matrix:
-                php: [7.4, 8.0, 8.1, 8.2]
+                php: [8.2, 8.3]
                 experimental: [false]
                 include:
-                    - php: 8.1
+                    - php: 8.3
                       analysis: true
 
         steps:
diff --git a/README.md b/README.md
index 63f99725..09681f18 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,7 @@ This skeleton application was built for Composer. This makes setting up a new Sl
 
 ## Install the Application
 
-Run this command from the directory in which you want to install your new Slim Framework application. You will require PHP 7.4 or newer.
+Run this command from the directory in which you want to install your new Slim Framework application. You will require PHP 8.3 or newer.
 
 ```bash
 composer create-project slim/slim-skeleton [my-app-name]
diff --git a/composer.json b/composer.json
index b74219b9..37a3f127 100644
--- a/composer.json
+++ b/composer.json
@@ -22,7 +22,7 @@
         }
     ],
     "require": {
-        "php": "^7.4 || ^8.0",
+        "php": "^8.2",
         "ext-json": "*",
         "monolog/monolog": "^2.9",
         "php-di/php-di": "^6.4",
diff --git a/public/index.php b/public/index.php
index bc583c82..75a37322 100644
--- a/public/index.php
+++ b/public/index.php
@@ -16,7 +16,7 @@
 $containerBuilder = new ContainerBuilder();
 
 if (false) { // Should be set to true in production
-	$containerBuilder->enableCompilation(__DIR__ . '/../var/cache');
+    $containerBuilder->enableCompilation(__DIR__ . '/../var/cache');
 }
 
 // Set up settings
diff --git a/src/Application/Actions/Action.php b/src/Application/Actions/Action.php
index 1021c202..bd146cbb 100644
--- a/src/Application/Actions/Action.php
+++ b/src/Application/Actions/Action.php
@@ -13,17 +13,17 @@
 
 abstract class Action
 {
-    protected LoggerInterface $logger;
-
     protected Request $request;
 
     protected Response $response;
 
+    /**
+     * @var array<string, mixed>
+     */
     protected array $args;
 
-    public function __construct(LoggerInterface $logger)
+    public function __construct(protected LoggerInterface $logger)
     {
-        $this->logger = $logger;
     }
 
     /**
@@ -49,10 +49,7 @@ public function __invoke(Request $request, Response $response, array $args): Res
      */
     abstract protected function action(): Response;
 
-    /**
-     * @return array|object
-     */
-    protected function getFormData()
+    protected function getFormData(): array|object|null
     {
         return $this->request->getParsedBody();
     }
@@ -70,10 +67,7 @@ protected function resolveArg(string $name)
         return $this->args[$name];
     }
 
-    /**
-     * @param array|object|null $data
-     */
-    protected function respondWithData($data = null, int $statusCode = 200): Response
+    protected function respondWithData(array|object|null $data = null, int $statusCode = 200): Response
     {
         $payload = new ActionPayload($statusCode, $data);
 
@@ -87,6 +81,6 @@ protected function respond(ActionPayload $payload): Response
 
         return $this->response
                     ->withHeader('Content-Type', 'application/json')
-                    ->withStatus($payload->getStatusCode());
+                    ->withStatus($payload->statusCode);
     }
 }
diff --git a/src/Application/Actions/ActionError.php b/src/Application/Actions/ActionError.php
index 3a81cc53..8b36f36c 100644
--- a/src/Application/Actions/ActionError.php
+++ b/src/Application/Actions/ActionError.php
@@ -18,36 +18,10 @@ class ActionError implements JsonSerializable
     public const VALIDATION_ERROR = 'VALIDATION_ERROR';
     public const VERIFICATION_ERROR = 'VERIFICATION_ERROR';
 
-    private string $type;
-
-    private ?string $description;
-
-    public function __construct(string $type, ?string $description = null)
-    {
-        $this->type = $type;
-        $this->description = $description;
-    }
-
-    public function getType(): string
-    {
-        return $this->type;
-    }
-
-    public function setType(string $type): self
-    {
-        $this->type = $type;
-        return $this;
-    }
-
-    public function getDescription(): ?string
-    {
-        return $this->description;
-    }
-
-    public function setDescription(?string $description = null): self
-    {
-        $this->description = $description;
-        return $this;
+    public function __construct(
+        public readonly string $type,
+        public readonly ?string $description = null
+    ) {
     }
 
     #[\ReturnTypeWillChange]
diff --git a/src/Application/Actions/ActionPayload.php b/src/Application/Actions/ActionPayload.php
index cbf51104..6137e4a2 100644
--- a/src/Application/Actions/ActionPayload.php
+++ b/src/Application/Actions/ActionPayload.php
@@ -8,41 +8,11 @@
 
 class ActionPayload implements JsonSerializable
 {
-    private int $statusCode;
-
-    /**
-     * @var array|object|null
-     */
-    private $data;
-
-    private ?ActionError $error;
-
     public function __construct(
-        int $statusCode = 200,
-        $data = null,
-        ?ActionError $error = null
+        public readonly int $statusCode = 200,
+        public readonly array|object|null $data = null,
+        public ?ActionError $error = null
     ) {
-        $this->statusCode = $statusCode;
-        $this->data = $data;
-        $this->error = $error;
-    }
-
-    public function getStatusCode(): int
-    {
-        return $this->statusCode;
-    }
-
-    /**
-     * @return array|null|object
-     */
-    public function getData()
-    {
-        return $this->data;
-    }
-
-    public function getError(): ?ActionError
-    {
-        return $this->error;
     }
 
     #[\ReturnTypeWillChange]
diff --git a/src/Application/Actions/User/UserAction.php b/src/Application/Actions/User/UserAction.php
index 4ea2d8ca..dbc7ae8f 100644
--- a/src/Application/Actions/User/UserAction.php
+++ b/src/Application/Actions/User/UserAction.php
@@ -10,11 +10,10 @@
 
 abstract class UserAction extends Action
 {
-    protected UserRepository $userRepository;
-
-    public function __construct(LoggerInterface $logger, UserRepository $userRepository)
-    {
+    public function __construct(
+        LoggerInterface $logger,
+        protected UserRepository $userRepository
+    ) {
         parent::__construct($logger);
-        $this->userRepository = $userRepository;
     }
 }
diff --git a/src/Application/Handlers/HttpErrorHandler.php b/src/Application/Handlers/HttpErrorHandler.php
index 64e02b1e..275bbad9 100644
--- a/src/Application/Handlers/HttpErrorHandler.php
+++ b/src/Application/Handlers/HttpErrorHandler.php
@@ -26,27 +26,25 @@ protected function respond(): Response
     {
         $exception = $this->exception;
         $statusCode = 500;
-        $error = new ActionError(
-            ActionError::SERVER_ERROR,
-            'An internal error has occurred while processing your request.'
-        );
+        $errorType = ActionError::SERVER_ERROR;
+        $description = 'An internal error has occurred while processing your request.';
 
         if ($exception instanceof HttpException) {
             $statusCode = $exception->getCode();
-            $error->setDescription($exception->getMessage());
+            $description = $exception->getMessage();
 
             if ($exception instanceof HttpNotFoundException) {
-                $error->setType(ActionError::RESOURCE_NOT_FOUND);
+                $errorType = ActionError::RESOURCE_NOT_FOUND;
             } elseif ($exception instanceof HttpMethodNotAllowedException) {
-                $error->setType(ActionError::NOT_ALLOWED);
+                $errorType = ActionError::NOT_ALLOWED;
             } elseif ($exception instanceof HttpUnauthorizedException) {
-                $error->setType(ActionError::UNAUTHENTICATED);
+                $errorType = ActionError::UNAUTHENTICATED;
             } elseif ($exception instanceof HttpForbiddenException) {
-                $error->setType(ActionError::INSUFFICIENT_PRIVILEGES);
+                $errorType = ActionError::INSUFFICIENT_PRIVILEGES;
             } elseif ($exception instanceof HttpBadRequestException) {
-                $error->setType(ActionError::BAD_REQUEST);
+                $errorType = ActionError::BAD_REQUEST;
             } elseif ($exception instanceof HttpNotImplementedException) {
-                $error->setType(ActionError::NOT_IMPLEMENTED);
+                $errorType = ActionError::NOT_IMPLEMENTED;
             }
         }
 
@@ -55,9 +53,10 @@ protected function respond(): Response
             && $exception instanceof Throwable
             && $this->displayErrorDetails
         ) {
-            $error->setDescription($exception->getMessage());
+            $description = $exception->getMessage();
         }
 
+        $error = new ActionError($errorType, $description);
         $payload = new ActionPayload($statusCode, null, $error);
         $encodedPayload = json_encode($payload, JSON_PRETTY_PRINT);
 
diff --git a/src/Application/Handlers/ShutdownHandler.php b/src/Application/Handlers/ShutdownHandler.php
index 72b6d46e..2f9b58eb 100644
--- a/src/Application/Handlers/ShutdownHandler.php
+++ b/src/Application/Handlers/ShutdownHandler.php
@@ -10,20 +10,11 @@
 
 class ShutdownHandler
 {
-    private Request $request;
-
-    private HttpErrorHandler $errorHandler;
-
-    private bool $displayErrorDetails;
-
     public function __construct(
-        Request $request,
-        HttpErrorHandler $errorHandler,
-        bool $displayErrorDetails
+        private Request $request,
+        private HttpErrorHandler $errorHandler,
+        private bool $displayErrorDetails
     ) {
-        $this->request = $request;
-        $this->errorHandler = $errorHandler;
-        $this->displayErrorDetails = $displayErrorDetails;
     }
 
     public function __invoke()
@@ -47,7 +38,10 @@ public function __invoke()
         $responseEmitter->emit($response);
     }
 
-    private function getErrorMessage(array $error): string
+    /**
+     * @param array{type: int, message: string, file: string, line: int} $error
+     */
+    private function getErrorMessage(array $error = null): string
     {
         if (!$this->displayErrorDetails) {
             return 'An error while processing your request. Please try again later.';
@@ -58,18 +52,10 @@ private function getErrorMessage(array $error): string
         $errorMessage = $error['message'];
         $errorType = $error['type'];
 
-        if ($errorType === E_USER_ERROR) {
-            return "FATAL ERROR: {$errorMessage}. on line {$errorLine} in file {$errorFile}.";
-        }
-
-        if ($errorType === E_USER_WARNING) {
-            return "WARNING: {$errorMessage}";
-        }
-
-        if ($errorType === E_USER_NOTICE) {
-            return "NOTICE: {$errorMessage}";
-        }
-
-        return "FATAL ERROR: {$errorMessage}. on line {$errorLine} in file {$errorFile}.";
+        return match ($errorType) {
+            E_USER_WARNING => "WARNING: {$errorMessage}",
+            E_USER_NOTICE => "NOTICE: {$errorMessage}",
+            default => "FATAL ERROR: {$errorMessage}. on line {$errorLine} in file {$errorFile}."
+        };
     }
 }
diff --git a/src/Application/Settings/Settings.php b/src/Application/Settings/Settings.php
index 6da55e4e..40017532 100644
--- a/src/Application/Settings/Settings.php
+++ b/src/Application/Settings/Settings.php
@@ -6,18 +6,16 @@
 
 class Settings implements SettingsInterface
 {
-    private array $settings;
-
-    public function __construct(array $settings)
+    /**
+     * @param array<string, mixed> $settings
+     */
+    public function __construct(private array $settings)
     {
         $this->settings = $settings;
     }
 
-    /**
-     * @return mixed
-     */
-    public function get(string $key = '')
+    public function get(string $key = ''): mixed
     {
-        return (empty($key)) ? $this->settings : $this->settings[$key];
+        return empty($key) ? $this->settings : $this->settings[$key];
     }
 }
diff --git a/src/Application/Settings/SettingsInterface.php b/src/Application/Settings/SettingsInterface.php
index 557d98b8..7867c592 100644
--- a/src/Application/Settings/SettingsInterface.php
+++ b/src/Application/Settings/SettingsInterface.php
@@ -6,9 +6,5 @@
 
 interface SettingsInterface
 {
-    /**
-     * @param string $key
-     * @return mixed
-     */
-    public function get(string $key = '');
+    public function get(string $key = ''): mixed;
 }
diff --git a/src/Domain/User/User.php b/src/Domain/User/User.php
index 217bb9eb..e01e8366 100644
--- a/src/Domain/User/User.php
+++ b/src/Domain/User/User.php
@@ -8,17 +8,18 @@
 
 class User implements JsonSerializable
 {
-    private ?int $id;
-
     private string $username;
 
     private string $firstName;
 
     private string $lastName;
 
-    public function __construct(?int $id, string $username, string $firstName, string $lastName)
-    {
-        $this->id = $id;
+    public function __construct(
+        private int|null $id,
+        string $username,
+        string $firstName,
+        string $lastName
+    ) {
         $this->username = strtolower($username);
         $this->firstName = ucfirst($firstName);
         $this->lastName = ucfirst($lastName);