replaced ~ by null

symfony/framework-bundle/3.3/config/packages/cache.yaml

@@ -16,4 +16,4 @@ framework:
 
         # Namespaced pools use the above "app" backend by default
         #pools:
-            #my.dedicated.cache: ~
+            #my.dedicated.cache: null

symfony/framework-bundle/3.3/config/packages/framework.yaml

@@ -6,7 +6,7 @@ framework:
     # Enables session support. Note that the session will ONLY be started if you read or write from it.
     # Remove or comment this section to explicitly disable session support.
     session:
-        handler_id: ~
+        handler_id: null
 
     #esi: true
     #fragments: true

symfony/framework-bundle/4.2/config/packages/framework.yaml

@@ -6,7 +6,7 @@ framework:
     # Enables session support. Note that the session will ONLY be started if you read or write from it.
     # Remove or comment this section to explicitly disable session support.
     session:
-        handler_id: ~
+        handler_id: null
         cookie_secure: auto
         cookie_samesite: lax