diff --git a/framework/yii/YiiBase.php b/framework/yii/YiiBase.php
index 4f85cae..ee75822 100644
--- a/framework/yii/YiiBase.php
+++ b/framework/yii/YiiBase.php
@@ -6,7 +6,6 @@
  */
 namespace yii;
 
-use yii\base\Arrayable;
 use yii\base\Exception;
 use yii\base\InvalidConfigException;
 use yii\base\InvalidParamException;
@@ -624,6 +623,19 @@ class YiiBase
 			$object->$name = $value;
 		}
 	}
+
+	/**
+	 * Returns the public member variables of an object.
+	 * This method is provided such that we can get the public member variables of an object.
+	 * It is different from "get_object_vars()" because the latter will return private
+	 * and protected variables if it is called within the object itself.
+	 * @param object $object the object to be handled
+	 * @return array the public member variables of the object
+	 */
+	public static function getObjectVars($object)
+	{
+		return get_object_vars($object);
+	}
 }
 
 YiiBase::$aliases = array(
diff --git a/framework/yii/base/ErrorHandler.php b/framework/yii/base/ErrorHandler.php
index 1e6671b..338a392 100644
--- a/framework/yii/base/ErrorHandler.php
+++ b/framework/yii/base/ErrorHandler.php
@@ -90,6 +90,8 @@ class ErrorHandler extends Component
 		$useErrorView = !YII_DEBUG || $exception instanceof UserException;
 
 		$response = Yii::$app->getResponse();
+		$response->getHeaders()->removeAll();
+
 		if ($useErrorView && $this->errorAction !== null) {
 			$result = Yii::$app->runAction($this->errorAction);
 			if ($result instanceof Response) {
diff --git a/framework/yii/base/Exception.php b/framework/yii/base/Exception.php
index fe497a7..4f66e53 100644
--- a/framework/yii/base/Exception.php
+++ b/framework/yii/base/Exception.php
@@ -29,11 +29,34 @@ class Exception extends \Exception implements Arrayable
 	 */
 	public function toArray()
 	{
-		return array(
-			'type' => get_class($this),
-			'name' => $this->getName(),
-			'message' => $this->getMessage(),
-			'code' => $this->getCode(),
-		);
+		return $this->toArrayRecursive($this);
+	}
+
+	/**
+	 * Returns the array representation of the exception and all previous exceptions recursively.
+	 * @param \Exception exception object
+	 * @return array the array representation of the exception.
+	 */
+	protected function toArrayRecursive($exception)
+	{
+		if ($exception instanceof self) {
+			$array = array(
+				'type' => get_class($this),
+				'name' => $this->getName(),
+				'message' => $this->getMessage(),
+				'code' => $this->getCode(),
+			);
+		} else {
+			$array = array(
+				'type' => get_class($exception),
+				'name' => 'Exception',
+				'message' => $exception->getMessage(),
+				'code' => $exception->getCode(),
+			);
+		}
+		if (($prev = $exception->getPrevious()) !== null) {
+			$array['previous'] = $this->toArrayRecursive($prev);
+		}
+		return $array;
 	}
 }
diff --git a/framework/yii/base/Object.php b/framework/yii/base/Object.php
index b7ab710..7724008 100644
--- a/framework/yii/base/Object.php
+++ b/framework/yii/base/Object.php
@@ -8,7 +8,6 @@
 namespace yii\base;
 
 use Yii;
-use yii\helpers\ArrayHelper;
 
 /**
  * @include @yii/base/Object.md
@@ -223,11 +222,10 @@ class Object implements Arrayable
 	/**
 	 * Converts the object into an array.
 	 * The default implementation will return all public property values as an array.
-	 * However, if the object is traversable, it will return the data obtained by the data iteration.
 	 * @return array the array representation of the object
 	 */
 	public function toArray()
 	{
-		return ArrayHelper::toArray($this, false);
+		return Yii::getObjectVars($this);
 	}
 }