diff --git a/src/Symfony/Component/Debug/CHANGELOG.md b/src/Symfony/Component/Debug/CHANGELOG.md
index 122af73174bf4..2b7bfc8ba30ed 100644
--- a/src/Symfony/Component/Debug/CHANGELOG.md
+++ b/src/Symfony/Component/Debug/CHANGELOG.md
@@ -1,6 +1,11 @@
 CHANGELOG
 =========
 
+4.3.0
+-----
+
+* made the `ErrorHandler` and `ExceptionHandler` classes final
+
 4.0.0
 -----
 
diff --git a/src/Symfony/Component/Debug/ErrorHandler.php b/src/Symfony/Component/Debug/ErrorHandler.php
index 912839bc472e2..972fc3a29772f 100644
--- a/src/Symfony/Component/Debug/ErrorHandler.php
+++ b/src/Symfony/Component/Debug/ErrorHandler.php
@@ -45,6 +45,8 @@
  *
  * @author Nicolas Grekas <p@tchwork.com>
  * @author Grégoire Pineau <lyrixx@lyrixx.info>
+ *
+ * @final since Symfony 4.3
  */
 class ErrorHandler
 {
diff --git a/src/Symfony/Component/Debug/ExceptionHandler.php b/src/Symfony/Component/Debug/ExceptionHandler.php
index ea666b1ac3863..259fb548939d1 100644
--- a/src/Symfony/Component/Debug/ExceptionHandler.php
+++ b/src/Symfony/Component/Debug/ExceptionHandler.php
@@ -26,6 +26,8 @@
  *
  * @author Fabien Potencier <fabien@symfony.com>
  * @author Nicolas Grekas <p@tchwork.com>
+ *
+ * @final since Symfony 4.3
  */
 class ExceptionHandler
 {