Fixed #18656

Author: brandonkelly

CHANGELOG.md

@@ -15,6 +15,7 @@
 - Fixed a bug where recent changes could be lost when creating an element or applying a draft, if there were validation errors. ([#18657](https://github.com/craftcms/cms/issues/18657))
 - Fixed a bug where nested elements would get soft-deleted after running the `entrify/global-set` command. ([#18650](https://github.com/craftcms/cms/issues/18650))
 - Fixed a bug where the “Max Authors” section setting was visible for Single sections.
+- Fixed an exception that would be thrown when attempting to access undefined keys within `craft\fields\data\JsonData` objects from Twig. ([#18656](https://github.com/craftcms/cms/issues/18656))
 
 ## 5.9.18 - 2026-03-26
 

src/fields/data/JsonData.php

@@ -16,6 +16,7 @@
 use Traversable;
 use yii\base\BaseObject;
 use yii\base\InvalidCallException;
+use yii\base\UnknownMethodException;
 
 /**
  * JSON field data class.
@@ -38,6 +39,20 @@ public function __toString(): string
         return $this->getJson();
     }
 
+    public function __call($name, $params)
+    {
+        try {
+            return parent::__call($name, $params);
+        } catch (UnknownMethodException $e) {
+            if (!empty($params)) {
+                throw $e;
+            }
+
+            // This is probably just Twig falling back to calling a properly like it's a method
+            return null;
+        }
+    }
+
     public function getType(): string
     {
         $type = gettype($this->value);