diff --git a/UPGRADE-2.5.md b/UPGRADE-2.5.md
index 69f57506fa..8776670dad 100644
--- a/UPGRADE-2.5.md
+++ b/UPGRADE-2.5.md
@@ -45,6 +45,18 @@ Form
    {
    ```
 
+   Before:
+
+   ```
+   {% if form.vars.errors %}
+   ```
+
+   After:
+
+   ```
+   {% if form.vars.errors|length %}
+   ```
+
 PropertyAccess
 --------------