diff --git a/src/Application/ErrorPresenter.php b/src/Application/ErrorPresenter.php
index e348d5ce4..7a1b40a3b 100644
--- a/src/Application/ErrorPresenter.php
+++ b/src/Application/ErrorPresenter.php
@@ -9,6 +9,7 @@
 
 use Nette;
 use Nette\Application;
+use Nette\Http;
 use Tracy\ILogger;
 
 
@@ -43,8 +44,10 @@ public function run(Application\Request $request)
 				$this->logger->log($e, ILogger::EXCEPTION);
 			}
 		}
-		return new Application\Responses\CallbackResponse(function () use ($code) {
-			require __DIR__ . '/templates/error.phtml';
+		return new Application\Responses\CallbackResponse(function (Http\IRequest $httpRequest, Http\IResponse $httpResponse) use ($code) {
+			if (preg_match('#^text/html(?:;|$)#', $httpResponse->getHeader('Content-Type'))) {
+				require __DIR__ . '/templates/error.phtml';
+			}
 		});
 	}
 }
diff --git a/src/Application/Request.php b/src/Application/Request.php
index 63712c254..37ed10bc4 100644
--- a/src/Application/Request.php
+++ b/src/Application/Request.php
@@ -32,6 +32,9 @@ class Request
 	/** flag */
 	const RESTORED = 'restored';
 
+	/** flag */
+	const VARYING = 'varying';
+
 	/** @var string|null */
 	private $method;
 
diff --git a/src/Application/Routers/Route.php b/src/Application/Routers/Route.php
index 0461256c2..a7ae9b663 100644
--- a/src/Application/Routers/Route.php
+++ b/src/Application/Routers/Route.php
@@ -728,7 +728,7 @@ private static function renameKeys($arr, $xlat)
 	 * @param  string
 	 * @return string
 	 */
-	private static function action2path($s)
+	public static function action2path($s)
 	{
 		$s = preg_replace('#(.)(?=[A-Z])#', '$1-', $s);
 		$s = strtolower($s);
@@ -742,7 +742,7 @@ private static function action2path($s)
 	 * @param  string
 	 * @return string
 	 */
-	private static function path2action($s)
+	public static function path2action($s)
 	{
 		$s = preg_replace('#-(?=[a-z])#', ' ', $s);
 		$s = lcfirst(ucwords($s));
@@ -756,7 +756,7 @@ private static function path2action($s)
 	 * @param  string
 	 * @return string
 	 */
-	private static function presenter2path($s)
+	public static function presenter2path($s)
 	{
 		$s = strtr($s, ':', '.');
 		$s = preg_replace('#([^.])(?=[A-Z])#', '$1-', $s);
@@ -771,7 +771,7 @@ private static function presenter2path($s)
 	 * @param  string
 	 * @return string
 	 */
-	private static function path2presenter($s)
+	public static function path2presenter($s)
 	{
 		$s = preg_replace('#([.-])(?=[a-z])#', '$1 ', $s);
 		$s = ucwords($s);
@@ -786,7 +786,7 @@ private static function path2presenter($s)
 	 * @param  string
 	 * @return string
 	 */
-	private static function param2path($s)
+	public static function param2path($s)
 	{
 		return str_replace('%2F', '/', rawurlencode($s));
 	}
diff --git a/src/Application/UI/Multiplier.php b/src/Application/UI/Multiplier.php
index 528e62e34..79a07dccd 100644
--- a/src/Application/UI/Multiplier.php
+++ b/src/Application/UI/Multiplier.php
@@ -7,7 +7,6 @@
 
 namespace Nette\Application\UI;
 
-use Nette;
 
 
 /**
diff --git a/src/Application/UI/Presenter.php b/src/Application/UI/Presenter.php
index 0203fcea8..bbb9f23f6 100644
--- a/src/Application/UI/Presenter.php
+++ b/src/Application/UI/Presenter.php
@@ -43,6 +43,9 @@ abstract class Presenter extends Control implements Application\IPresenter
 	/** @var int */
 	public $invalidLinkMode;
 
+	/** @var callable[]  function (Presenter $sender); Occurs when the presenter is starting */
+	public $onStartup;
+
 	/** @var callable[]  function (Presenter $sender, IResponse $response = null); Occurs when the presenter is shutting down */
 	public $onShutdown;
 
@@ -180,6 +183,7 @@ public function run(Application\Request $request)
 
 			$this->initGlobalParameters();
 			$this->checkRequirements($this->getReflection());
+			$this->onStartup($this);
 			$this->startup();
 			if (!$this->startupCheck) {
 				$class = $this->getReflection()->getMethod('startup')->getDeclaringClass()->getName();
@@ -735,18 +739,20 @@ public function getLastCreatedRequestFlag($flag)
 	 */
 	public function canonicalize($destination = null, array $args = [])
 	{
-		if (!$this->isAjax() && ($this->request->isMethod('get') || $this->request->isMethod('head'))) {
+		$request = $this->request;
+		if (!$this->isAjax() && ($request->isMethod('get') || $request->isMethod('head'))) {
 			try {
 				$url = $this->createRequest(
 					$this,
 					$destination ?: $this->action,
-					$args + $this->getGlobalState() + $this->request->getParameters(),
+					$args + $this->getGlobalState() + $request->getParameters(),
 					'redirectX'
 				);
 			} catch (InvalidLinkException $e) {
 			}
 			if (isset($url) && !$this->httpRequest->getUrl()->isEqual($url)) {
-				$this->sendResponse(new Responses\RedirectResponse($url, Http\IResponse::S301_MOVED_PERMANENTLY));
+				$code = $request->hasFlag($request::VARYING) ? Http\IResponse::S302_FOUND : Http\IResponse::S301_MOVED_PERMANENTLY;
+				$this->sendResponse(new Responses\RedirectResponse($url, $code));
 			}
 		}
 	}
diff --git a/tests/UI/Presenter.formatLayoutTemplateFiles.phpt b/tests/UI/Presenter.formatLayoutTemplateFiles.phpt
index a57a72577..a271e31a1 100644
--- a/tests/UI/Presenter.formatLayoutTemplateFiles.phpt
+++ b/tests/UI/Presenter.formatLayoutTemplateFiles.phpt
@@ -4,7 +4,6 @@
  * Test: Presenter::formatLayoutTemplateFiles.
  */
 
-use Nette\Application\UI\Presenter;
 use Tester\Assert;
 
 
diff --git a/tests/UI/Presenter.formatTemplateFiles.phpt b/tests/UI/Presenter.formatTemplateFiles.phpt
index 2c107436e..c2bd996f7 100644
--- a/tests/UI/Presenter.formatTemplateFiles.phpt
+++ b/tests/UI/Presenter.formatTemplateFiles.phpt
@@ -4,7 +4,6 @@
  * Test: Presenter::formatTemplateFiles.
  */
 
-use Nette\Application\UI\Presenter;
 use Tester\Assert;