diff --git a/core/lib/Drupal/Core/EventSubscriber/HttpExceptionSubscriberBase.php b/core/lib/Drupal/Core/EventSubscriber/HttpExceptionSubscriberBase.php
index 4e230f4..d6143be 100644
--- a/core/lib/Drupal/Core/EventSubscriber/HttpExceptionSubscriberBase.php
+++ b/core/lib/Drupal/Core/EventSubscriber/HttpExceptionSubscriberBase.php
@@ -92,7 +92,6 @@ public function onException(GetResponseForExceptionEvent $event) {
     $handled_formats = $this->getHandledFormats();
 
     $format = $request->query->get(MainContentViewSubscriber::WRAPPER_ENVELOPE) ?: $request->getRequestFormat();
-    debug($format);
 
     if ($exception instanceof HttpExceptionInterface && (empty($handled_formats) || in_array($format, $handled_formats))) {
       $method = 'on' . $exception->getStatusCode();
diff --git a/core/lib/Drupal/Core/EventSubscriber/MainContentViewSubscriber.php b/core/lib/Drupal/Core/EventSubscriber/MainContentViewSubscriber.php
index cbdce65..625d2a6 100644
--- a/core/lib/Drupal/Core/EventSubscriber/MainContentViewSubscriber.php
+++ b/core/lib/Drupal/Core/EventSubscriber/MainContentViewSubscriber.php
@@ -85,9 +85,9 @@ public function onViewRenderArray(GetResponseForControllerResultEvent $event) {
 
     // Render the controller result into a response if it's a render array.
     if (is_array($result)) {
-      // We default to getRequestFormat() because content negotiation uses this as
-      // its fallback method for displaying a 406 when we fail to match a route
-      // based on format.
+      // We default to getRequestFormat() because content negotiation uses this
+      // as its fallback method for displaying a 406 when we fail to match a
+      // route based on format.
       // @todo this logic should be replaced with a more clear opt in to avoid
       //    cache poisoning. https://www.drupal.org/node/2364011
       $wrapper = $request->query->get(static::WRAPPER_ENVELOPE, $request->getRequestFormat());
diff --git a/core/lib/Drupal/Core/Routing/RequestFormatMatcher.php b/core/lib/Drupal/Core/Routing/RequestFormatMatcher.php
index d27fc62..a29deb7 100644
--- a/core/lib/Drupal/Core/Routing/RequestFormatMatcher.php
+++ b/core/lib/Drupal/Core/Routing/RequestFormatMatcher.php
@@ -27,7 +27,7 @@ public function filter(RouteCollection $collection, Request $request) {
     if ($format = $request->getRequestFormat('html')) {
       foreach ($collection as $name => $route) {
         // If its not a match, we move the route to the end, so we effectively
-        // Move the matching route to the front.
+        // move the matching route to the front.
         $supported_formats = array_filter(explode('|', $route->getRequirement('_format')));
         if (!in_array($format, $supported_formats)) {
           $collection->add($name, $route);
diff --git a/core/modules/page_cache/src/Tests/PageCacheTest.php b/core/modules/page_cache/src/Tests/PageCacheTest.php
index bebcbab..6e55e12 100644
--- a/core/modules/page_cache/src/Tests/PageCacheTest.php
+++ b/core/modules/page_cache/src/Tests/PageCacheTest.php
@@ -79,7 +79,8 @@ function testPageCacheTags() {
   }
 
   /**
-   * Tests support for different cache items with different request formats specified via a query parameter.
+   * Tests support for different cache items with different request formats
+   * specified via a query parameter.
    */
   function testQueryParameterFormatRequests() {
     $config = $this->config('system.performance');
diff --git a/core/modules/system/src/Tests/Routing/ContentNegotiationRoutingTest.php b/core/modules/system/src/Tests/Routing/ContentNegotiationRoutingTest.php
index 8eb8ecb..71cbc30 100644
--- a/core/modules/system/src/Tests/Routing/ContentNegotiationRoutingTest.php
+++ b/core/modules/system/src/Tests/Routing/ContentNegotiationRoutingTest.php
@@ -68,25 +68,25 @@ function testContentRouting() {
       // No extension. Constant Content-type.
       ['conneg/html', '', 'text/html', FALSE],
       ['conneg/html', '*/*', 'text/html', FALSE],
-      // @TODO We have to turn of full content negotiation to support this.
+      // @todo We have to turn of full content negotiation to support this.
       ['conneg/html', 'application/xml', 'text/html', FALSE],
       ['conneg/html', 'text/xml', 'text/html', FALSE],
       ['conneg/html', 'text/html', 'text/html', FALSE],
       // Dynamic extension. Linked Content-type.
-      // @TODO We have to turn of full content negotiation to support this.
+      // @todo We have to turn of full content negotiation to support this.
       ['conneg/html?_format=json', '', 'application/json', FALSE],
       ['conneg/html?_format=json', '*/*', 'application/json', FALSE],
       ['conneg/html?_format=json', 'application/xml', 'application/json', FALSE],
       ['conneg/html?_format=json', 'application/json', 'application/json', FALSE],
-      // @TODO We have to turn of full content negotiation to support this.
+      // @todo We have to turn of full content negotiation to support this.
       ['conneg/html?_format=xml', '', 'application/xml', FALSE],
       ['conneg/html?_format=xml', '*/*', 'application/xml', FALSE],
       ['conneg/html?_format=xml', 'application/json', 'application/xml', FALSE],
       ['conneg/html?_format=xml', 'application/xml', 'application/xml', FALSE],
-      // @TODO a Drupal vendor protocol?
+      // @todo a Drupal vendor protocol?
 
       // Path with a variable. Variable contains a period.
-      // @TODO We have to turn of full content negotiation to support these.
+      // @todo We have to turn of full content negotiation to support these.
       ['conneg/plugin/plugin.id', '', 'text/html', FALSE],
       ['conneg/plugin/plugin.id', '*/*', 'text/html', FALSE],
       ['conneg/plugin/plugin.id', 'text/xml', 'text/html', FALSE],
@@ -106,7 +106,7 @@ function testContentRouting() {
 //      ['alias.json', 'application/json', 'application/json', FALSE],
 
       // Alias with extension pointing to dynamic extension/linked content-type.
-      // @TODO how to test aliasing? Can we just assume aliasing does its thing?
+      // @todo how to test aliasing? Can we just assume aliasing does its thing?
       // this might not even work :(
     ];
 
@@ -120,8 +120,9 @@ function testContentRouting() {
       /** @var \Symfony\Component\HttpKernel\HttpKernelInterface $kernel */
       $kernel = \Drupal::getContainer()->get('http_kernel');
       $response = $kernel->handle($request);
-
-      $this->assertTrue(TRUE, $message); // verbose message since simpletest doesn't let us provide a message and see the error.
+      // Verbose message since simpletest doesn't let us provide a message and
+      // see the error.
+      $this->assertTrue(TRUE, $message);
       $this->assertEqual($response->getStatusCode(), Response::HTTP_OK);
       $this->assertTrue(strpos($response->headers->get('Content-type'), $test[2]) !== FALSE);
 
@@ -156,8 +157,9 @@ public function ptestFullNegotiation() {
       /** @var \Symfony\Component\HttpKernel\HttpKernelInterface $kernel */
       $kernel = \Drupal::getContainer()->get('http_kernel');
       $response = $kernel->handle($request);
-
-      $this->assertTrue(TRUE, $message); // verbose message since simpletest doesn't let us provide a message and see the error.
+      // Verbose message since simpletest doesn't let us provide a message and
+      // see the error.
+      $this->assertTrue(TRUE, $message);
       $this->assertEqual($response->getStatusCode(), Response::HTTP_OK);
       $this->assertEqual($response->headers->get('Content-type'), $test[2]);
       $this->assertEqual($response->headers->get('Cache-Control'), 'public');
@@ -177,7 +179,8 @@ public function ptestContentRouting400() {
         'text/html',
         Response::HTTP_NOT_ACCEPTABLE
       ],
-      // TODO negotiate a content type no support by the path but supported by error handler.
+      // @todo negotiate a content type no support by the path but supported by
+      // error handler.
 
       ['conneg/html.dne', 'vnd/dne', 'text/html', Response::HTTP_NOT_FOUND],
     ];
@@ -191,7 +194,9 @@ public function ptestContentRouting400() {
       $kernel = \Drupal::getContainer()->get('http_kernel');
       $response = $kernel->handle($request);
 
-      $this->assertTrue(TRUE, $message); // verbose message since simpletest doesn't let us provide a message and see the error.
+      // Verbose message since simpletest doesn't let us provide a message and
+      // see the error.
+      $this->assertTrue(TRUE, $message);
       $this->assertEqual($response->getStatusCode(), $test[3]);
       $this->assertEqual($response->headers->get('Content-type'), $test[2]);
     }
diff --git a/core/modules/system/tests/modules/ajax_test/src/Controller/AjaxTestController.php b/core/modules/system/tests/modules/ajax_test/src/Controller/AjaxTestController.php
index ad5adc3..e7da745 100644
--- a/core/modules/system/tests/modules/ajax_test/src/Controller/AjaxTestController.php
+++ b/core/modules/system/tests/modules/ajax_test/src/Controller/AjaxTestController.php
@@ -121,7 +121,7 @@ public function dialog() {
       '#url' => Url::fromRoute('ajax_test.dialog_contents'),
       '#attributes' => array(
         'class' => array('use-ajax'),
-        'data-accepts' => 'application/vnd.drupal-modal', // TODO replace this.
+        'data-accepts' => 'application/vnd.drupal-modal', // @todo replace this.
       ),
     );