diff --git a/UPGRADE.md b/UPGRADE.md
index 27d2b96c..85152f69 100644
--- a/UPGRADE.md
+++ b/UPGRADE.md
@@ -226,3 +226,9 @@
 ```bash
     bin/console doctrine:migrations:migrate --no-interaction
 ```
+
+1. The visibility of services has been changed to `private` by default. This change enhances the performance
+   and maintainability of the application and also follows Symfony's best practices for service encapsulation.
+
+   Exceptions:
+   - Services required by Symfony to be `public` (e.g., controllers, event listeners) remain public.
diff --git a/config/services.xml b/config/services.xml
index d5678946..3c74a68c 100644
--- a/config/services.xml
+++ b/config/services.xml
@@ -1,6 +1,21 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
-<container xmlns="http://symfony.com/schema/dic/services" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
+<!--
+
+ This file is part of the Sylius package.
+
+ (c) Sylius Sp. z o.o.
+
+ For the full copyright and license information, please view the LICENSE
+ file that was distributed with this source code.
+
+-->
+
+<container
+    xmlns="http://symfony.com/schema/dic/services"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd"
+>
     <imports>
         <import resource="services/**/*.xml" />
     </imports>
@@ -11,8 +26,6 @@
     </parameters>
 
     <services>
-        <defaults public="true" />
-
         <service id="sylius_invoicing.email.invoice_email_sender" class="Sylius\InvoicingPlugin\Email\InvoiceEmailSender">
             <argument type="service" id="sylius.email_sender" />
             <argument type="service" id="sylius_invoicing.provider.invoice_file" />
diff --git a/config/services/actions.xml b/config/services/actions.xml
index 28f6ca61..be58bdbc 100644
--- a/config/services/actions.xml
+++ b/config/services/actions.xml
@@ -1,6 +1,21 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
-<container xmlns="http://symfony.com/schema/dic/services" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
+<!--
+
+ This file is part of the Sylius package.
+
+ (c) Sylius Sp. z o.o.
+
+ For the full copyright and license information, please view the LICENSE
+ file that was distributed with this source code.
+
+-->
+
+<container
+    xmlns="http://symfony.com/schema/dic/services"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd"
+>
     <services>
         <defaults public="true" />
 
diff --git a/config/services/cli.xml b/config/services/cli.xml
index c57e1268..ed6cb0c0 100644
--- a/config/services/cli.xml
+++ b/config/services/cli.xml
@@ -1,6 +1,21 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
-<container xmlns="http://symfony.com/schema/dic/services" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
+<!--
+
+ This file is part of the Sylius package.
+
+ (c) Sylius Sp. z o.o.
+
+ For the full copyright and license information, please view the LICENSE
+ file that was distributed with this source code.
+
+-->
+
+<container
+    xmlns="http://symfony.com/schema/dic/services"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd"
+>
     <services>
         <defaults public="true" />
 
diff --git a/config/services/converters.xml b/config/services/converters.xml
index 05ceeeea..e28df52e 100644
--- a/config/services/converters.xml
+++ b/config/services/converters.xml
@@ -1,9 +1,22 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
-<container xmlns="http://symfony.com/schema/dic/services" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
-    <services>
-        <defaults public="true" />
+<!--
+
+ This file is part of the Sylius package.
+
+ (c) Sylius Sp. z o.o.
 
+ For the full copyright and license information, please view the LICENSE
+ file that was distributed with this source code.
+
+-->
+
+<container
+    xmlns="http://symfony.com/schema/dic/services"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd"
+>
+    <services>
         <service id="sylius_invoicing.converter.order_item_units_to_line_items" class="Sylius\InvoicingPlugin\Converter\OrderItemUnitsToLineItemsConverter">
             <argument type="service" id="sylius_invoicing.provider.tax_rate_percentage" />
             <argument type="service" id="sylius_invoicing.factory.line_item" />
diff --git a/config/services/fixtures.xml b/config/services/fixtures.xml
index 92ff6603..841d0ede 100644
--- a/config/services/fixtures.xml
+++ b/config/services/fixtures.xml
@@ -1,9 +1,22 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
-<container xmlns="http://symfony.com/schema/dic/services" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
-    <services>
-        <defaults public="true" />
+<!--
+
+ This file is part of the Sylius package.
+
+ (c) Sylius Sp. z o.o.
 
+ For the full copyright and license information, please view the LICENSE
+ file that was distributed with this source code.
+
+-->
+
+<container
+    xmlns="http://symfony.com/schema/dic/services"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd"
+>
+    <services>
         <service id="sylius_invoicing.fixture.example_factory.invoicing_plugin_shop_billing_data" class="Sylius\InvoicingPlugin\Fixture\Factory\ShopBillingDataExampleFactory">
             <argument id="sylius.repository.channel" type="service"/>
             <argument id="sylius.factory.shop_billing_data" type="service"/>
diff --git a/config/services/generators.xml b/config/services/generators.xml
index b66c1576..3c314fe5 100644
--- a/config/services/generators.xml
+++ b/config/services/generators.xml
@@ -1,9 +1,22 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
-<container xmlns="http://symfony.com/schema/dic/services" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
-    <services>
-        <defaults public="true" />
+<!--
+
+ This file is part of the Sylius package.
+
+ (c) Sylius Sp. z o.o.
 
+ For the full copyright and license information, please view the LICENSE
+ file that was distributed with this source code.
+
+-->
+
+<container
+    xmlns="http://symfony.com/schema/dic/services"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd"
+>
+    <services>
         <service id="sylius_invoicing.generator.invoice_number" class="Sylius\InvoicingPlugin\Generator\SequentialInvoiceNumberGenerator">
             <argument type="service" id="sylius_invoicing.repository.invoice_sequence" />
             <argument type="service" id="sylius_invoicing.factory.invoice_sequence" />
diff --git a/config/services/listeners.xml b/config/services/listeners.xml
index 727560b3..988881bd 100644
--- a/config/services/listeners.xml
+++ b/config/services/listeners.xml
@@ -1,6 +1,21 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
-<container xmlns="http://symfony.com/schema/dic/services" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
+<!--
+
+ This file is part of the Sylius package.
+
+ (c) Sylius Sp. z o.o.
+
+ For the full copyright and license information, please view the LICENSE
+ file that was distributed with this source code.
+
+-->
+
+<container
+    xmlns="http://symfony.com/schema/dic/services"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd"
+>
     <services>
         <defaults public="true" />
 
diff --git a/config/services/listeners/workflow.xml b/config/services/listeners/workflow.xml
index c9245b42..199b0148 100644
--- a/config/services/listeners/workflow.xml
+++ b/config/services/listeners/workflow.xml
@@ -1,6 +1,21 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
-<container xmlns="http://symfony.com/schema/dic/services" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
+<!--
+
+ This file is part of the Sylius package.
+
+ (c) Sylius Sp. z o.o.
+
+ For the full copyright and license information, please view the LICENSE
+ file that was distributed with this source code.
+
+-->
+
+<container
+    xmlns="http://symfony.com/schema/dic/services"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd"
+>
     <services>
         <defaults public="true" />
 
diff --git a/config/services/ui.xml b/config/services/ui.xml
index f81d1284..7459c8bd 100644
--- a/config/services/ui.xml
+++ b/config/services/ui.xml
@@ -1,6 +1,21 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
-<container xmlns="http://symfony.com/schema/dic/services" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
+<!--
+
+ This file is part of the Sylius package.
+
+ (c) Sylius Sp. z o.o.
+
+ For the full copyright and license information, please view the LICENSE
+ file that was distributed with this source code.
+
+-->
+
+<container
+    xmlns="http://symfony.com/schema/dic/services"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd"
+>
     <services>
         <defaults public="true" />