diff --git a/framework/YiiBase.php b/framework/YiiBase.php
index 678856c..16e237d 100644
--- a/framework/YiiBase.php
+++ b/framework/YiiBase.php
@@ -298,7 +298,7 @@ class YiiBase
 			}
 		}
 
-		if (isset($classFile, $alias)) {
+		if (isset($classFile, $alias) && is_file($classFile)) {
 			if (!YII_DEBUG || basename(realpath($classFile)) === basename($alias) . '.php') {
 				include($classFile);
 				return true;
diff --git a/framework/base/Component.php b/framework/base/Component.php
index 515f7e1..2d081d3 100644
--- a/framework/base/Component.php
+++ b/framework/base/Component.php
@@ -58,7 +58,7 @@ class Component extends \yii\base\Object
 				}
 			}
 		}
-		throw new UnknownPropertyException('Getting unknown property: ' . get_class($this) . '.' . $name);
+		throw new UnknownPropertyException('Getting unknown property: ' . get_class($this) . '::' . $name);
 	}
 
 	/**
@@ -105,9 +105,9 @@ class Component extends \yii\base\Object
 			}
 		}
 		if (method_exists($this, 'get' . $name)) {
-			throw new InvalidCallException('Setting read-only property: ' . get_class($this) . '.' . $name);
+			throw new InvalidCallException('Setting read-only property: ' . get_class($this) . '::' . $name);
 		} else {
-			throw new UnknownPropertyException('Setting unknown property: ' . get_class($this) . '.' . $name);
+			throw new UnknownPropertyException('Setting unknown property: ' . get_class($this) . '::' . $name);
 		}
 	}
 
diff --git a/framework/base/Object.php b/framework/base/Object.php
index f589e38..3bd8378 100644
--- a/framework/base/Object.php
+++ b/framework/base/Object.php
@@ -65,7 +65,7 @@ class Object
 		if (method_exists($this, $getter)) {
 			return $this->$getter();
 		} else {
-			throw new UnknownPropertyException('Getting unknown property: ' . get_class($this) . '.' . $name);
+			throw new UnknownPropertyException('Getting unknown property: ' . get_class($this) . '::' . $name);
 		}
 	}
 
@@ -86,9 +86,9 @@ class Object
 		if (method_exists($this, $setter)) {
 			$this->$setter($value);
 		} elseif (method_exists($this, 'get' . $name)) {
-			throw new InvalidCallException('Setting read-only property: ' . get_class($this) . '.' . $name);
+			throw new InvalidCallException('Setting read-only property: ' . get_class($this) . '::' . $name);
 		} else {
-			throw new UnknownPropertyException('Setting unknown property: ' . get_class($this) . '.' . $name);
+			throw new UnknownPropertyException('Setting unknown property: ' . get_class($this) . '::' . $name);
 		}
 	}
 
@@ -129,7 +129,7 @@ class Object
 		if (method_exists($this, $setter)) {
 			$this->$setter(null);
 		} elseif (method_exists($this, 'get' . $name)) {
-			throw new InvalidCallException('Unsetting read-only property: ' . get_class($this) . '.' . $name);
+			throw new InvalidCallException('Unsetting read-only property: ' . get_class($this) . '::' . $name);
 		}
 	}
 
diff --git a/framework/base/View.php b/framework/base/View.php
index 7170251..c7087c1 100644
--- a/framework/base/View.php
+++ b/framework/base/View.php
@@ -45,11 +45,21 @@ class View extends Component
 	 * through this property.
 	 */
 	public $clips;
-
 	/**
-	 * @var Widget[] the widgets that are currently not ended
+	 * @var Widget[] the widgets that are currently being rendered (not ended). This property
+	 * is maintained by [[beginWidget()]] and [[endWidget()]] methods. Do not modify it directly.
+	 */
+	public $widgetStack = array();
+	/**
+	 * @var array a list of currently active fragment cache widgets. This property
+	 * is used internally to implement the content caching feature. Do not modify it.
+	 */
+	public $cacheStack = array();
+	/**
+	 * @var array a list of placeholders for embedding dynamic contents. This property
+	 * is used internally to implement the content caching feature. Do not modify it.
 	 */
-	private $_widgetStack = array();
+	public $dynamicPlaceholders = array();
 
 
 	/**
@@ -156,20 +166,47 @@ class View extends Component
 		return ob_get_clean();
 	}
 
+	/**
+	 * Renders dynamic content returned by the given PHP statements.
+	 * This method is mainly used together with content caching (fragment caching and page caching)
+	 * when some portions of the content (called *dynamic content*) should not be cached.
+	 * The dynamic content must be returned by some PHP statements.
+	 * @param string $statements the PHP statements for generating the dynamic content.
+	 * @return string the placeholder of the dynamic content, or the dynamic content if there is no
+	 * active content cache currently.
+	 */
 	public function renderDynamic($statements)
 	{
-		if (!empty($this->cachingStack)) {
-			$n = count($this->_dynamicOutput);
+		if (!empty($this->cacheStack)) {
+			$n = count($this->dynamicPlaceholders);
 			$placeholder = "<![CDATA[YDP-$n]]>";
-			foreach ($this->cachingStack as $cache) {
-				$cache->dynamicPlaceholders[$placeholder] = $statements;
-			}
+			$this->addDynamicPlaceholder($placeholder, $statements);
 			return $placeholder;
 		} else {
 			return $this->evaluateDynamicContent($statements);
 		}
 	}
 
+	/**
+	 * Adds a placeholder for dynamic content.
+	 * This method is internally used.
+	 * @param string $placeholder the placeholder name
+	 * @param string $statements the PHP statements for generating the dynamic content
+	 */
+	public function addDynamicPlaceholder($placeholder, $statements)
+	{
+		foreach ($this->cacheStack as $cache) {
+			$cache->dynamicPlaceholders[$placeholder] = $statements;
+		}
+		$this->dynamicPlaceholders[$placeholder] = $statements;
+	}
+
+	/**
+	 * Evaluates the given PHP statements.
+	 * This method is mainly used internally to implement dynamic content feature.
+	 * @param string $statements the PHP statements to be evaluated.
+	 * @return mixed the return value of the PHP statements.
+	 */
 	public function evaluateDynamicContent($statements)
 	{
 		return eval($statements);
@@ -267,7 +304,7 @@ class View extends Component
 	public function beginWidget($class, $properties = array())
 	{
 		$widget = $this->createWidget($class, $properties);
-		$this->_widgetStack[] = $widget;
+		$this->widgetStack[] = $widget;
 		return $widget;
 	}
 
@@ -281,7 +318,7 @@ class View extends Component
 	 */
 	public function endWidget()
 	{
-		$widget = array_pop($this->_widgetStack);
+		$widget = array_pop($this->widgetStack);
 		if ($widget instanceof Widget) {
 			$widget->run();
 			return $widget;
@@ -363,8 +400,9 @@ class View extends Component
 	public function beginCache($id, $properties = array())
 	{
 		$properties['id'] = $id;
+		$properties['view'] = $this;
 		/** @var $cache \yii\widgets\FragmentCache */
-		$cache = $this->beginWidget('yii\widgets\OutputCache', $properties);
+		$cache = $this->beginWidget('yii\widgets\FragmentCache', $properties);
 		if ($cache->getCachedContent() !== false) {
 			$this->endCache();
 			return false;
diff --git a/framework/widgets/FragmentCache.php b/framework/widgets/FragmentCache.php
index b56b86f..3bb321e 100644
--- a/framework/widgets/FragmentCache.php
+++ b/framework/widgets/FragmentCache.php
@@ -67,7 +67,8 @@ class FragmentCache extends Widget
 	 */
 	public $view;
 	/**
-	 * @var array
+	 * @var array a list of placeholders for embedding dynamic contents. This property
+	 * is used internally to implement the content caching feature. Do not modify it.
 	 */
 	public $dynamicPlaceholders;
 
@@ -83,8 +84,8 @@ class FragmentCache extends Widget
 		if ($this->view === null) {
 			$this->view = Yii::$app->getView();
 		}
-		if ($this->getCachedContent() === false && $this->getCache() !== null) {
-			array_push($this->view->cachingStack, $this);
+		if ($this->getCache() !== null && $this->getCachedContent() === false) {
+			$this->view->cacheStack[] = $this;
 			ob_start();
 			ob_implicit_flush(false);
 		}
@@ -100,14 +101,18 @@ class FragmentCache extends Widget
 	{
 		if (($content = $this->getCachedContent()) !== false) {
 			echo $content;
-		} elseif (($cache = $this->getCache()) !== false) {
+		} elseif (($cache = $this->getCache()) !== null) {
 			$content = ob_get_clean();
-			array_pop($this->view->cachingStack);
+			array_pop($this->view->cacheStack);
 			if (is_array($this->dependency)) {
 				$this->dependency = Yii::createObject($this->dependency);
 			}
 			$data = array($content, $this->dynamicPlaceholders);
 			$cache->set($this->calculateKey(), $data, $this->duration, $this->dependency);
+
+			if ($this->view->cacheStack === array() && !empty($this->dynamicPlaceholders)) {
+				$content = $this->updateDynamicContent($content, $this->dynamicPlaceholders);
+			}
 			echo $content;
 		}
 	}
@@ -131,10 +136,13 @@ class FragmentCache extends Widget
 				if (is_array($data) && count($data) === 2) {
 					list ($content, $placeholders) = $data;
 					if (is_array($placeholders) && count($placeholders) > 0) {
+						if ($this->view->cacheStack === array()) {
+							// outermost cache: replace placeholder with dynamic content
+							$content = $this->updateDynamicContent($content, $placeholders);
+						}
 						foreach ($placeholders as $name => $statements) {
-							$placeholders[$name] = $this->view->evaluateDynamicContent($statements);
+							$this->view->addDynamicPlaceholder($name, $statements);
 						}
-						$content = strtr($content, $placeholders);
 					}
 					$this->_content = $content;
 				}
@@ -143,6 +151,14 @@ class FragmentCache extends Widget
 		return $this->_content;
 	}
 
+	protected function updateDynamicContent($content, $placeholders)
+	{
+		foreach ($placeholders as $name => $statements) {
+			$placeholders[$name] = $this->view->evaluateDynamicContent($statements);
+		}
+		return strtr($content, $placeholders);
+	}
+
 	/**
 	 * Generates a unique key used for storing the content in cache.
 	 * The key generated depends on both [[id]] and [[variations]].