diff --git a/core/lib/Drupal/Core/Template/Attribute.php b/core/lib/Drupal/Core/Template/Attribute.php
index 846174d..3967cf8 100644
--- a/core/lib/Drupal/Core/Template/Attribute.php
+++ b/core/lib/Drupal/Core/Template/Attribute.php
@@ -99,6 +99,14 @@ protected function createAttributeValue($name, $value) {
     elseif (!is_object($value)) {
       $value = new AttributeString($name, $value);
     }
+    // Provide a better exception message when invalid object is passed as value.
+    elseif (is_object($value) && !method_exists($value, '__toString')) {
+      throw new \Exception(t('"@attribute_name" attribute value of type "@class" can not be converted to string', array(
+        '@attribute_name' => $name,
+        '@class' => get_class($value)
+      )));
+    }
+
     return $value;
   }
 
diff --git a/core/lib/Drupal/Core/Template/TwigNodeExpressionFunction.php b/core/lib/Drupal/Core/Template/TwigNodeExpressionFunction.php
new file mode 100644
index 0000000..3902abd
--- /dev/null
+++ b/core/lib/Drupal/Core/Template/TwigNodeExpressionFunction.php
@@ -0,0 +1,51 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Template\TwigNodeExpressionFunction.
+ *
+ *
+ */
+
+namespace Drupal\Core\Template;
+
+/**
+ * A class that extends Twig_Node_Expression_Function.
+ *
+ * Instances of this class are used in Drupal\Core\Template\TwigNodeVisitor
+ * to call the render_var function, with extra arguments.
+ *
+ * @see core\vendor\twig\twig\lib\Twig\Node\Expression\Function.php
+ */
+class TwigNodeExpressionFunction extends \Twig_Node_Expression_Function {
+  protected $extra_arguments;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function __construct($name, \Twig_NodeInterface $arguments, $extra_arguments, $lineno) {
+    parent::__construct($name, $arguments, $lineno);
+    $this->extra_arguments = $extra_arguments;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function compile(\Twig_Compiler $compiler) {
+    $name = $this->getAttribute('name');
+    $function = $compiler->getEnvironment()->getFunction($name);
+
+    $this->setAttribute('name', $name);
+    $this->setAttribute('type', 'function');
+    $this->setAttribute('thing', $function);
+    $this->setAttribute('needs_environment', $function->needsEnvironment());
+    $this->setAttribute('needs_context', $function->needsContext());
+    $this->setAttribute('arguments', array_merge($function->getArguments(), $this->extra_arguments));
+    if ($function instanceof \Twig_FunctionCallableInterface || $function instanceof \Twig_SimpleFunction) {
+      $this->setAttribute('callable', $function->getCallable());
+    }
+
+    $this->compileCallable($compiler);
+  }
+}
+
diff --git a/core/lib/Drupal/Core/Template/TwigNodeVisitor.php b/core/lib/Drupal/Core/Template/TwigNodeVisitor.php
index 4915c16..d4095a4 100644
--- a/core/lib/Drupal/Core/Template/TwigNodeVisitor.php
+++ b/core/lib/Drupal/Core/Template/TwigNodeVisitor.php
@@ -39,8 +39,9 @@ function leaveNode(\Twig_NodeInterface $node, \Twig_Environment $env) {
       }
       $class = get_class($node);
       $line = $node->getLine();
+      $name = $node->getNode('expr')->hasAttribute('name') ? $node->getNode('expr')->getAttribute('name') : 'Object';
       return new $class(
-        new \Twig_Node_Expression_Function('render_var', new \Twig_Node(array($node->getNode('expr'))), $line),
+        new TwigNodeExpressionFunction('render_var', new \Twig_Node(array($node->getNode('expr'))), array($name), $line),
         $line
       );
     }
diff --git a/core/themes/engines/twig/twig.engine b/core/themes/engines/twig/twig.engine
index e0cfcc2..c20da07 100644
--- a/core/themes/engines/twig/twig.engine
+++ b/core/themes/engines/twig/twig.engine
@@ -119,7 +119,7 @@ function twig_render_template($template_file, $variables) {
  * @see render
  * @see TwigNodeVisitor
  */
-function twig_render_var($arg) {
+function twig_render_var($arg_name, $arg) {
   // Check for numeric zero.
   if ($arg === 0) {
     return 0;
@@ -144,7 +144,7 @@ function twig_render_var($arg) {
       return (string) $arg;
     }
     else {
-      throw new Exception(t('Object of type "@class" cannot be printed.', array('@class' => get_class($arg))));
+      throw new Exception(t('@arg_name of type "@class" doesn\'t implement __toString.', array('@arg_name' => $arg_name, '@class' => get_class($arg))));
     }
   }