diff --git a/Civi/Twingle/Shop/BAO/TwingleProduct.php b/Civi/Twingle/Shop/BAO/TwingleProduct.php
index 355e369..7d47cdd 100644
--- a/Civi/Twingle/Shop/BAO/TwingleProduct.php
+++ b/Civi/Twingle/Shop/BAO/TwingleProduct.php
@@ -2,11 +2,13 @@
 
 namespace Civi\Twingle\Shop\BAO;
 
+use Civi\Api4\PriceField;
 use Civi\Twingle\Shop\DAO\TwingleProduct as TwingleProductDAO;
 use Civi\Twingle\Shop\DAO\TwingleShop as TwingleShopDAO;
 use Civi\Twingle\Shop\Exceptions\ProductException;
 use Civi\Twingle\Shop\Exceptions\ShopException;
 use CRM_Core_Exception;
+use CRM_Core_Transaction;
 use CRM_Twingle_ExtensionUtil as E;
 use CRM_Utils_Type;
 use function Civi\Twingle\Shop\Utils\convert_int_to_bool;
@@ -86,6 +88,7 @@ class TwingleProduct extends TwingleProductDAO {
     "twingle_shop_id",
     "financial_type_id",
     "price_field_id",
+    "project_id",
     "external_id",
     "tw_updated_at",
     "tw_created_at",
@@ -306,15 +309,12 @@ public function createPriceField($mode = 'create') {
     if ($mode == 'edit') {
       $price_field_data['id'] = $this->price_field_id;
     }
-
     try {
-      $price_field = civicrm_api3('PriceField', 'create', $price_field_data);
-      if ($price_field['is_error'] != 0) {
-        throw new ProductException(
-          E::ts('Could not create PriceField for this Twingle Product: %1',
-            [1 => $price_field['error_message']]),
-          ProductException::ERROR_CODE_COULD_NOT_CREATE_PRICE_FIELD);
-      }
+      $price_field = civicrm_api4(
+        'PriceField',
+        'create',
+        ['values' => $price_field_data],
+      )->first();
       $this->price_field_id = (int) $price_field['id'];
     }
     catch (CRM_Core_Exception $e) {
@@ -341,21 +341,24 @@ public function createPriceField($mode = 'create') {
     }
 
     // Create PriceFieldValue
+    $price_field_value_data = [
+      'price_field_id' => $this->price_field_id,
+      'financial_type_id' => $this->financial_type_id,
+      'label' => $this->name,
+      'amount' => $this->price,
+      'is_active' => $this->is_active,
+      'description' => $this->description,
+    ];
+    // Add id if in edit mode
+    if ($mode == 'edit' && $price_field_value) {
+      $price_field_value_data['id'] = $price_field_value['id'];
+    }
     try {
-      $price_field_value_data = [
-        'price_field_id' => $this->price_field_id,
-        'financial_type_id' => $this->financial_type_id,
-        'label' => $this->name,
-        'amount' => $this->price,
-        'is_active' => $this->is_active,
-        'description' => $this->description,
-      ];
-      // Add id if in edit mode
-      if ($mode == 'edit' && $price_field_value) {
-        $price_field_value_data['id'] = $price_field_value['id'];
-      }
-
-      civicrm_api3('PriceFieldValue', 'create', $price_field_value_data);
+      civicrm_api4(
+        'PriceFieldValue',
+        'create',
+        ['values' => $price_field_value_data],
+      );
     }
     catch (CRM_Core_Exception $e) {
       throw new ProductException(
@@ -406,11 +409,16 @@ public static function findByExternalId($external_id) {
   /**
    * Add Twingle Product
    *
+   * @param string $mode
+   *  'create' or 'edit'
    * @return array
    * @throws \Civi\Twingle\Shop\Exceptions\ProductException
    * @throws \Exception
    */
-  public function add() {
+  public function add($mode = 'create') {
+
+    $tx = new CRM_Core_Transaction();
+
     // Try to lookup object in database
     try {
       $dao = TwingleShopDAO::executeQuery("SELECT * FROM civicrm_twingle_product WHERE external_id = %1",
@@ -425,26 +433,27 @@ public function add() {
         ShopException::ERROR_CODE_COULD_NOT_FIND_SHOP_IN_DB);
     }
 
-    // Define hook type
-    $hook = $this->id ? 'edit' : 'create';
-
     // Register pre-hook
-    \CRM_Utils_Hook::pre($hook, 'TwingleProduct', $this->id);
-
-    // Create associated PriceField
-    $this->createPriceField($hook);
+    \CRM_Utils_Hook::pre($mode, 'TwingleProduct', $this->id);
 
     // Set latest tw_updated_at as new updated_at
     $this->updated_at = \CRM_Utils_Time::date('Y-m-d H:i:s', $this->tw_updated_at);
 
     // Save object to database
-    $this->save();
+    try {
+      $this->save();
+    } catch (\Exception $e) {
+      $tx->rollback();
+      throw new ProductException(
+        E::ts('Could not save TwingleProduct to database: ' . $e->getMessage()),
+        ProductException::ERROR_CODE_COULD_NOT_CREATE_PRODUCT);
+    }
     $result = self::findById($this->id);
     /* @var self $result */
     $this->load($result->getAttributes());
 
     // Register post-hook
-    \CRM_Utils_Hook::post($hook, 'TwingleProduct', $this->id, $instance);
+    \CRM_Utils_Hook::post($mode, 'TwingleProduct', $this->id, $instance);
 
     return $result->toArray();
   }
diff --git a/Civi/Twingle/Shop/BAO/TwingleShop.php b/Civi/Twingle/Shop/BAO/TwingleShop.php
index b8f1a23..0656118 100644
--- a/Civi/Twingle/Shop/BAO/TwingleShop.php
+++ b/Civi/Twingle/Shop/BAO/TwingleShop.php
@@ -131,10 +131,12 @@ function getAttributes(): array {
   /**
    * Add Twingle Shop
    *
+   * @param string $mode
+   *  'create' or 'edit'
    * @return array
    * @throws \Civi\Twingle\Shop\Exceptions\ShopException
    */
-  public function add() {
+  public function add($mode = 'create') {
 
     // Try to lookup object in database
     try {
@@ -149,20 +151,14 @@ public function add() {
         ShopException::ERROR_CODE_COULD_NOT_FIND_SHOP_IN_DB);
     }
 
-    // Define hook type
-    $hook = $this->id ? 'edit' : 'create';
-
     // Register pre-hook
-    \CRM_Utils_Hook::pre($hook, 'TwingleShop', $this->id);
-
-    // Create associated PriceSet
-    $this->createPriceSet($hook);
+    \CRM_Utils_Hook::pre($mode, 'TwingleShop', $this->id);
 
     // Save object to database
     $result = $this->save();
 
     // Register post-hook
-    \CRM_Utils_Hook::post($hook, 'TwingleShop', $this->id, $instance);
+    \CRM_Utils_Hook::post($mode, 'TwingleShop', $this->id, $instance);
 
     return $result->toArray();
   }
@@ -310,6 +306,8 @@ public function getProducts() {
   /**
    * Creates Twingle Shop as a price set in CiviCRM.
    *
+   * @param string $mode
+   *  'create' or 'edit'
    * @throws \Civi\Twingle\Shop\Exceptions\ShopException
    */
   public function createPriceSet($mode = 'create') {
diff --git a/Civi/Twingle/Shop/Exceptions/ProductException.php b/Civi/Twingle/Shop/Exceptions/ProductException.php
index e156970..c208ca2 100644
--- a/Civi/Twingle/Shop/Exceptions/ProductException.php
+++ b/Civi/Twingle/Shop/Exceptions/ProductException.php
@@ -20,6 +20,6 @@ class ProductException extends BaseException {
   public const ERROR_CODE_COULD_NOT_DELETE_PRICE_FIELD = 'price_field_deletion_failed';
   public const ERROR_CODE_COULD_NOT_DELETE_PRICE_FIELD_VALUE = 'price_field_value_deletion_failed';
   public const ERROR_CODE_PRICE_FIELD_STILL_EXISTS = 'price_field_still_exists';
-  public const ERROR_CODE_PRICE_FIELD_VALUE_STILL_EXISTS = 'price_field_still_exists';
+  public const ERROR_CODE_COULD_NOT_CREATE_PRODUCT = 'product_creation_failed';
 
 }
diff --git a/api/v3/TwingleProduct/Create.php b/api/v3/TwingleProduct/Create.php
index 9a5d7d6..0c246eb 100644
--- a/api/v3/TwingleProduct/Create.php
+++ b/api/v3/TwingleProduct/Create.php
@@ -110,8 +110,14 @@ function civicrm_api3_twingle_product_Create($params): array {
     $product = new TwingleProduct();
     $product->load($params);
 
+    // Define mode
+    $mode = $product->id ? 'edit' : 'create';
+
+    // Create associated PriceField
+    $product->createPriceField($mode);
+
     // Save TwingleProduct
-    $product->add();
+    $product->add($mode);
     $result = $product->getAttributes();
     return civicrm_api3_create_success($result, $params, 'TwingleProduct', 'Create');
   }
diff --git a/api/v3/TwingleShop/Create.php b/api/v3/TwingleShop/Create.php
index ebb34f4..4aa74b7 100644
--- a/api/v3/TwingleShop/Create.php
+++ b/api/v3/TwingleShop/Create.php
@@ -65,8 +65,14 @@ function civicrm_api3_twingle_shop_Create($params) {
     $shop = new TwingleShop();
     $shop->load($params);
 
+    // Define mode
+    $mode = $shop->id ? 'edit' : 'create';
+
+    // Create associated PriceSet
+    $shop->createPriceSet($mode);
+
     // Save TwingleShop
-    $result = $shop->add();
+    $result = $shop->add($mode);
 
     // Return success
     return civicrm_api3_create_success($result, $params, 'TwingleShop', 'Create');
diff --git a/sql/civicrm_twingle_shop.sql b/sql/civicrm_twingle_shop.sql
index 9a811a2..918b0ef 100644
--- a/sql/civicrm_twingle_shop.sql
+++ b/sql/civicrm_twingle_shop.sql
@@ -60,7 +60,7 @@ CREATE TABLE `civicrm_twingle_product` (
                                          `created_at` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT 'Timestamp of when the product was created in the database',
                                          `updated_at` datetime NOT NULL COMMENT 'Timestamp of when the product was last updated in the Twingle database',
                                          PRIMARY KEY (`id`),
-                                         CONSTRAINT FK_civicrm_twingle_product_price_field_id FOREIGN KEY (`price_field_id`) REFERENCES `civicrm_contact`(`id`) ON DELETE CASCADE,
+                                         CONSTRAINT FK_civicrm_twingle_product_price_field_id FOREIGN KEY (`price_field_id`) REFERENCES `civicrm_price_field`(`id`) ON DELETE CASCADE,
                                          CONSTRAINT FK_civicrm_twingle_product_twingle_shop_id FOREIGN KEY (`twingle_shop_id`) REFERENCES `civicrm_twingle_shop`(`id`) ON DELETE CASCADE
 )
   ENGINE=InnoDB;