diff --git a/lib/Db/AppointmentConfigMapper.php b/lib/Db/AppointmentConfigMapper.php
index 0f2722c40..c2be450c1 100644
--- a/lib/Db/AppointmentConfigMapper.php
+++ b/lib/Db/AppointmentConfigMapper.php
@@ -90,7 +90,7 @@ class AppointmentConfigMapper extends QBMapper {
 	 * @return AppointmentConfig[]
 	 * @throws DbException
 	 */
-	public function findAllForUser(string $userId, string $visibility = null): array {
+	public function findAllForUser(string $userId, ?string $visibility = null): array {
 		$qb = $this->db->getQueryBuilder();
 		$qb->select('*')
 			->from($this->getTableName())
diff --git a/lib/Exception/ClientException.php b/lib/Exception/ClientException.php
index 7e2407164..09ce0431f 100644
--- a/lib/Exception/ClientException.php
+++ b/lib/Exception/ClientException.php
@@ -34,8 +34,8 @@ class ClientException extends Exception {
 
 	public function __construct($message = "",
 		$code = 0,
-		Throwable $previous = null,
-		int $httpCode = null) {
+		?Throwable $previous = null,
+		?int $httpCode = null) {
 		parent::__construct($message, $code, $previous);
 		$this->httpCode = $httpCode;
 	}
diff --git a/lib/Exception/ServiceException.php b/lib/Exception/ServiceException.php
index f8a01594c..780541da4 100644
--- a/lib/Exception/ServiceException.php
+++ b/lib/Exception/ServiceException.php
@@ -32,8 +32,8 @@ class ServiceException extends Exception {
 
 	public function __construct($message = "",
 		$code = 0,
-		Throwable $previous = null,
-		int $httpCode = null) {
+		?Throwable $previous = null,
+		?int $httpCode = null) {
 		parent::__construct($message, $code, $previous);
 		$this->httpCode = $httpCode;
 	}
diff --git a/lib/Service/Appointments/AppointmentConfigService.php b/lib/Service/Appointments/AppointmentConfigService.php
index a45b3cb23..809d4f316 100644
--- a/lib/Service/Appointments/AppointmentConfigService.php
+++ b/lib/Service/Appointments/AppointmentConfigService.php
@@ -59,7 +59,7 @@ class AppointmentConfigService {
 	 * @return AppointmentConfig[]
 	 * @throws ServiceException
 	 */
-	public function getAllAppointmentConfigurations(string $userId, string $visibility = null): array {
+	public function getAllAppointmentConfigurations(string $userId, ?string $visibility = null): array {
 		try {
 			return $this->mapper->findAllForUser($userId, $visibility);
 		} catch (DbException $e) {
diff --git a/vendor-bin/cs-fixer/composer.json b/vendor-bin/cs-fixer/composer.json
index 2960a1105..7404364d5 100644
--- a/vendor-bin/cs-fixer/composer.json
+++ b/vendor-bin/cs-fixer/composer.json
@@ -6,6 +6,6 @@
         "sort-packages": true
     },
     "require-dev": {
-        "nextcloud/coding-standard": "^1.1.1"
+        "nextcloud/coding-standard": "^1.2.1"
     }
 }
diff --git a/vendor-bin/cs-fixer/composer.lock b/vendor-bin/cs-fixer/composer.lock
index 2a84d1eae..cb055698d 100644
--- a/vendor-bin/cs-fixer/composer.lock
+++ b/vendor-bin/cs-fixer/composer.lock
@@ -4,21 +4,21 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "a2b3a9be8be756074466a5fa651aa0ef",
+    "content-hash": "1db99a21f71fb454322d63fba47a3c5f",
     "packages": [],
     "packages-dev": [
         {
             "name": "nextcloud/coding-standard",
-            "version": "v1.1.1",
+            "version": "v1.2.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/nextcloud/coding-standard.git",
-                "reference": "55def702fb9a37a219511e1d8c6fe8e37164c1fb"
+                "reference": "cf5f18d989ec62fb4cdc7fc92a36baf34b3d829e"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/nextcloud/coding-standard/zipball/55def702fb9a37a219511e1d8c6fe8e37164c1fb",
-                "reference": "55def702fb9a37a219511e1d8c6fe8e37164c1fb",
+                "url": "https://api.github.com/repos/nextcloud/coding-standard/zipball/cf5f18d989ec62fb4cdc7fc92a36baf34b3d829e",
+                "reference": "cf5f18d989ec62fb4cdc7fc92a36baf34b3d829e",
                 "shasum": ""
             },
             "require": {
@@ -44,22 +44,22 @@
             "description": "Nextcloud coding standards for the php cs fixer",
             "support": {
                 "issues": "https://github.com/nextcloud/coding-standard/issues",
-                "source": "https://github.com/nextcloud/coding-standard/tree/v1.1.1"
+                "source": "https://github.com/nextcloud/coding-standard/tree/v1.2.1"
             },
-            "time": "2023-06-01T12:05:01+00:00"
+            "time": "2024-02-01T14:54:37+00:00"
         },
         {
             "name": "php-cs-fixer/shim",
-            "version": "v3.17.0",
+            "version": "v3.49.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/PHP-CS-Fixer/shim.git",
-                "reference": "f51b4aed90565c447136f1d015798f6f7c82490f"
+                "reference": "f7d3219cac46632f12362c9aa7c2ac0d2fe92c52"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/PHP-CS-Fixer/shim/zipball/f51b4aed90565c447136f1d015798f6f7c82490f",
-                "reference": "f51b4aed90565c447136f1d015798f6f7c82490f",
+                "url": "https://api.github.com/repos/PHP-CS-Fixer/shim/zipball/f7d3219cac46632f12362c9aa7c2ac0d2fe92c52",
+                "reference": "f7d3219cac46632f12362c9aa7c2ac0d2fe92c52",
                 "shasum": ""
             },
             "require": {
@@ -96,9 +96,9 @@
             "description": "A tool to automatically fix PHP code style",
             "support": {
                 "issues": "https://github.com/PHP-CS-Fixer/shim/issues",
-                "source": "https://github.com/PHP-CS-Fixer/shim/tree/v3.17.0"
+                "source": "https://github.com/PHP-CS-Fixer/shim/tree/v3.49.0"
             },
-            "time": "2023-05-22T20:00:38+00:00"
+            "time": "2024-02-02T00:42:09+00:00"
         }
     ],
     "aliases": [],
@@ -109,7 +109,7 @@
     "platform": [],
     "platform-dev": [],
     "platform-overrides": {
-        "php": "7.4"
+        "php": "8.0"
     },
-    "plugin-api-version": "2.3.0"
+    "plugin-api-version": "2.6.0"
 }