diff --git a/UPGRADE-3.1.md b/UPGRADE-3.1.md
index db3b491c00ad..8ecd0a4afe2c 100644
--- a/UPGRADE-3.1.md
+++ b/UPGRADE-3.1.md
@@ -103,11 +103,10 @@ FrameworkBundle
 
    ```yaml
    framework:
-       serializer: ~
-           cache:
-               pools:
-                   serializer:
-                       adapter: cache.adapter.apcu
+       cache:
+           pools:
+               serializer:
+                   adapter: cache.adapter.apcu
 
 HttpKernel
 ----------
diff --git a/UPGRADE-4.0.md b/UPGRADE-4.0.md
index 54b6fd19b5a9..14758b4ab4ef 100644
--- a/UPGRADE-4.0.md
+++ b/UPGRADE-4.0.md
@@ -93,11 +93,10 @@ FrameworkBundle
 
    ```yaml
    framework:
-       serializer: ~
-           cache:
-               pools:
-                   serializer:
-                       adapter: cache.adapter.apcu
+       cache:
+           pools:
+               serializer:
+                   adapter: cache.adapter.apcu
    ```
 
 HttpKernel