diff --git a/src/Endpoints/Orders.php b/src/Endpoints/Orders.php
index acfeafa..7f3d07f 100644
--- a/src/Endpoints/Orders.php
+++ b/src/Endpoints/Orders.php
@@ -25,7 +25,7 @@ public function getOrder(int $id): Order
         try {
             $response = $this->client->get('/orders/' . $id);
 
-            SendcloudRequestException::fromResponse($response);
+            SendcloudRequestException::fromResponse($response, 200);
 
             $body = $response->getBody()->getContents();
 
@@ -156,7 +156,7 @@ public function getOrders(
             // Send request
 
             $response = $this->client->get($uri);
-            SendcloudRequestException::fromResponse($response);
+            SendcloudRequestException::fromResponse($response, 200);
 
             // Parse response
 
@@ -195,7 +195,7 @@ public function updateOrder(
             $body = json_encode($order);
             $response = $this->client->patch('/orders/' . $order->id, [], $body);
 
-            SendcloudRequestException::fromResponse($response);
+            SendcloudRequestException::fromResponse($response, 200);
 
             $body = $response->getBody()->getContents();
             $json = json_decode($body, true);
@@ -224,7 +224,7 @@ public function createOrder(
             $body = json_encode($orders);
             $response = $this->client->post('/orders', [], $body);
 
-            SendcloudRequestException::fromResponse($response);
+            SendcloudRequestException::fromResponse($response, 201);
 
             $body = $response->getBody()->getContents();
             $json = json_decode($body, true);
@@ -252,7 +252,7 @@ public function deleteOrder(
         try {
             $response = $this->client->post('/orders/' . $id);
 
-            SendcloudRequestException::fromResponse($response);
+            SendcloudRequestException::fromResponse($response, 204);
         } catch (Throwable $throwable) {
             SendcloudRequestException::fromException($throwable);
         }
diff --git a/src/Exceptions/SendcloudRequestException.php b/src/Exceptions/SendcloudRequestException.php
index c869453..9f8dbb0 100644
--- a/src/Exceptions/SendcloudRequestException.php
+++ b/src/Exceptions/SendcloudRequestException.php
@@ -33,17 +33,27 @@ public function __construct(
         $message = $message ?? '';
         $code = $code ?? SendcloudRequestException::CODE_UNKNOWN;
 
+        if (isset($sendcloudCode)) {
+            $message .= sprintf(' [%s]', $sendcloudCode);
+        }
+
+        if (isset($sendcloudSource)) {
+            $message .= " (at " . json_encode($sendcloudSource) . ")";
+        }
+
         parent::__construct($message, $code, $previous);
     }
 
     /**
      * Checks response for errors code and throws exception if needed
+     * 
+     * @param $expected_status_code Expected HTTP status code in response
      *
      * @throws SendcloudRequestException
      */
-    public static function fromResponse(ResponseInterface $response) : void
+    public static function fromResponse(ResponseInterface $response, int $expected_status_code = 200) : void
     {
-        if ($response->getStatusCode() === 200) {
+        if ($response->getStatusCode() === $expected_status_code) {
             return;
         }
 
diff --git a/src/Factory/ClientFactory.php b/src/Factory/ClientFactory.php
index 537e400..535e2c8 100644
--- a/src/Factory/ClientFactory.php
+++ b/src/Factory/ClientFactory.php
@@ -51,7 +51,9 @@ public static function create(
 
         // Headers
 
-        $headers = [];
+        $headers = [
+            'Content-Type' => 'application/json'
+        ];
         if (isset($partnerId)) {
             $headers['Sendcloud-Partner-Id'] = $partnerId;
         }
diff --git a/src/Models/Order/OrderDetails.php b/src/Models/Order/OrderDetails.php
index c35ac34..cf0ec80 100644
--- a/src/Models/Order/OrderDetails.php
+++ b/src/Models/Order/OrderDetails.php
@@ -31,8 +31,8 @@ public function __construct(
         public readonly Status $status,
         public readonly DateTimeImmutable $order_created_at,
         public readonly array $order_items,
-        public readonly DateTimeImmutable $order_updated_at,
-        public readonly string $notes,
+        public readonly ?DateTimeImmutable $order_updated_at = null,
+        public readonly ?string $notes = null,
         public readonly ?array $tags = null
     ) {
 
@@ -50,8 +50,8 @@ public static function fromData(array $data) : self
             status: Status::fromData($data['status']),
             order_created_at: DateUtils::iso8601ToDateTime($data['order_created_at']),
             order_items: $order_items,
-            order_updated_at: DateUtils::iso8601ToDateTime($data['order_updated_at']),
-            notes: (string) $data['notes'],
+            order_updated_at: isset($data['order_updated_at']) ? DateUtils::iso8601ToDateTime($data['order_updated_at']) : null,
+            notes: isset($data['notes']) ? (string) $data['notes'] : null,
             tags: isset($data['tags']) ? $data['tags'] : null
         );
     }
@@ -62,12 +62,15 @@ public function jsonSerialize() : array
             'integration' => $this->integration,
             'status' => $this->status,
             'order_created_at' => DateUtils::dateTimeToIso8601($this->order_created_at),
-            'order_items' => $this->order_items,
-            'order_updated_at' => DateUtils::dateTimeToIso8601($this->order_updated_at),
-            'notes' => $this->notes
+            'order_items' => $this->order_items
         ];
 
+        if (isset($this->order_updated_at)) {
+            $json['order_updated_at'] = DateUtils::dateTimeToIso8601($this->order_updated_at);
+        }
+
         JsonUtils::addIfNotNull($json, 'tags', $this->tags);
+        JsonUtils::addIfNotNull($json, 'notes', $this->notes);
 
         return $json;
     }
diff --git a/tests/Endpoints/OrdersTest.php b/tests/Endpoints/OrdersTest.php
index 3090b39..6b385db 100644
--- a/tests/Endpoints/OrdersTest.php
+++ b/tests/Endpoints/OrdersTest.php
@@ -525,7 +525,7 @@ public function testCreateOrder() : void
             ]
         }
         JSON;
-        $endpoint = $this->getEndpoint($json, 200);
+        $endpoint = $this->getEndpoint($json, 201);
 
         // -- Act
 
@@ -561,7 +561,7 @@ public function testDeleteOrder() : void
         // -- Arrange
 
         $order_id = 1;
-        $endpoint = $this->getEndpoint('', 200);
+        $endpoint = $this->getEndpoint('', 204);
 
         // -- Act & Assert