diff --git a/UPGRADE-4.0.md b/UPGRADE-4.0.md
index ee9d187638..ea1a2613da 100644
--- a/UPGRADE-4.0.md
+++ b/UPGRADE-4.0.md
@@ -163,7 +163,18 @@ DependencyInjection
            autowire: true
     ```
 
- * Autowiring services based on the types they implement is not supported anymore. Rename (or alias) your services to their FQCN id to make them autowirable.
+ * Autowiring services based on the types they implement is not supported anymore.
+   It will only look for an alias or a service id that matches a given FQCN.
+   Rename (or alias) your services to their FQCN id to make them autowirable.
+   In 3.4, you can activate this behavior instead of having deprecation messages
+   by setting the following parameter:
+   
+   ```yml
+   parameters:
+       container.autowiring.strict_mode: true
+   ```
+   
+   From 4.0, you can remove it as it's the default behavior and the parameter is not handled anymore.
 
  * `_defaults` and `_instanceof` are now reserved service names in Yaml configurations. Please rename any services with that names.