diff --git a/core/modules/ckeditor/js/ckeditor.drupalimage.admin.js b/core/modules/ckeditor/js/ckeditor.drupalimage.admin.js
index 1315b24..2292e74 100644
--- a/core/modules/ckeditor/js/ckeditor.drupalimage.admin.js
+++ b/core/modules/ckeditor/js/ckeditor.drupalimage.admin.js
@@ -25,7 +25,7 @@
         var output = '';
         output += Drupal.t('Uploads enabled, max size: @size @dimensions', { '@size': maxFileSize, '@dimensions': maxDimensions });
         if ($scheme.length) {
-          output += '<br />' + $scheme.attr('data-label');
+          output += '<br>' + $scheme.attr('data-label');
         }
         return output;
       });
diff --git a/core/modules/ckeditor/src/Plugin/CKEditorPlugin/StylesCombo.php b/core/modules/ckeditor/src/Plugin/CKEditorPlugin/StylesCombo.php
index 2184cf2..8247857 100644
--- a/core/modules/ckeditor/src/Plugin/CKEditorPlugin/StylesCombo.php
+++ b/core/modules/ckeditor/src/Plugin/CKEditorPlugin/StylesCombo.php
@@ -79,7 +79,7 @@ public function settingsForm(array $form, array &$form_state, Editor $editor) {
       '#title_display' => 'invisible',
       '#type' => 'textarea',
       '#default_value' => $config['styles'],
-      '#description' => t('A list of classes that will be provided in the "Styles" dropdown. Enter one class on each line in the format: element.class|Label. Example: h1.title|Title.<br />These styles should be available in your theme\'s CSS file.'),
+      '#description' => t('A list of classes that will be provided in the "Styles" dropdown. Enter one class on each line in the format: element.class|Label. Example: h1.title|Title.<br>These styles should be available in your theme\'s CSS file.'),
       '#attached' => array(
         'library' => array('ckeditor/drupal.ckeditor.stylescombo.admin'),
       ),
diff --git a/core/modules/entity_reference/src/Plugin/views/row/EntityReference.php b/core/modules/entity_reference/src/Plugin/views/row/EntityReference.php
index b975b0a..156d77b 100644
--- a/core/modules/entity_reference/src/Plugin/views/row/EntityReference.php
+++ b/core/modules/entity_reference/src/Plugin/views/row/EntityReference.php
@@ -42,7 +42,7 @@ public function buildOptionsForm(&$form, &$form_state) {
     parent::buildOptionsForm($form, $form_state);
 
     // Expand the description of the 'Inline field' checkboxes.
-    $form['inline']['#description'] .= '<br />' . t("<strong>Note:</strong> In 'Entity Reference' displays, all fields will be displayed inline unless an explicit selection of inline fields is made here." );
+    $form['inline']['#description'] .= '<br>' . t("<strong>Note:</strong> In 'Entity Reference' displays, all fields will be displayed inline unless an explicit selection of inline fields is made here." );
   }
 
   /**
diff --git a/core/modules/field_ui/src/DisplayOverviewBase.php b/core/modules/field_ui/src/DisplayOverviewBase.php
index 2a6f46f..b373db3 100644
--- a/core/modules/field_ui/src/DisplayOverviewBase.php
+++ b/core/modules/field_ui/src/DisplayOverviewBase.php
@@ -398,7 +398,7 @@ protected function buildFieldRow(FieldDefinitionInterface $field_definition, Ent
 
         if (!empty($summary)) {
           $field_row['settings_summary'] = array(
-            '#markup' => '<div class="field-plugin-summary">' . implode('<br />', $summary) . '</div>',
+            '#markup' => '<div class="field-plugin-summary">' . implode('<br>', $summary) . '</div>',
             '#cell_attributes' => array('class' => array('field-plugin-summary-cell')),
           );
         }
diff --git a/core/modules/field_ui/src/Form/FieldInstanceEditForm.php b/core/modules/field_ui/src/Form/FieldInstanceEditForm.php
index 9c4de60..d96639d 100644
--- a/core/modules/field_ui/src/Form/FieldInstanceEditForm.php
+++ b/core/modules/field_ui/src/Form/FieldInstanceEditForm.php
@@ -122,7 +122,7 @@ public function buildForm(array $form, array &$form_state, FieldInstanceConfigIn
       '#title' => $this->t('Help text'),
       '#default_value' => $this->instance->getDescription(),
       '#rows' => 5,
-      '#description' => $this->t('Instructions to present to the user below this field on the editing form.<br />Allowed HTML tags: @tags', array('@tags' => _field_filter_xss_display_allowed_tags())) . '<br />' . $this->t('This field supports tokens.'),
+      '#description' => $this->t('Instructions to present to the user below this field on the editing form.<br>Allowed HTML tags: @tags', array('@tags' => _field_filter_xss_display_allowed_tags())) . '<br>' . $this->t('This field supports tokens.'),
       '#weight' => -10,
     );
 
diff --git a/core/modules/filter/src/Plugin/Filter/FilterHtml.php b/core/modules/filter/src/Plugin/Filter/FilterHtml.php
index 109d943..99df396 100644
--- a/core/modules/filter/src/Plugin/Filter/FilterHtml.php
+++ b/core/modules/filter/src/Plugin/Filter/FilterHtml.php
@@ -100,7 +100,7 @@ public function tips($long = FALSE) {
     $output .= '<p>' . $this->t('For more information see W3C\'s <a href="@html-specifications">HTML Specifications</a> or use your favorite search engine to find other sites that explain HTML.', array('@html-specifications' => 'http://www.w3.org/TR/html/')) . '</p>';
     $tips = array(
       'a' => array($this->t('Anchors are used to make links to other pages.'), '<a href="' . $base_url . '">' . check_plain(\Drupal::config('system.site')->get('name')) . '</a>'),
-      'br' => array($this->t('By default line break tags are automatically added, so use this tag to add additional ones. Use of this tag is different because it is not used with an open/close pair like all the others. Use the extra " /" inside the tag to maintain XHTML 1.0 compatibility'), $this->t('Text with <br />line break')),
+      'br' => array($this->t('By default line break tags are automatically added, so use this tag to add additional ones. Use of this tag is different because it is not used with an open/close pair like all the others.'), $this->t('Text with <br>line break')),
       'p' => array($this->t('By default paragraph tags are automatically added, so use this tag to add additional ones.'), '<p>' . $this->t('Paragraph one.') . '</p> <p>' . $this->t('Paragraph two.') . '</p>'),
       'strong' => array($this->t('Strong', array(), array('context' => 'Font weight')), '<strong>' . $this->t('Strong', array(), array('context' => 'Font weight')) . '</strong>'),
       'em' => array($this->t('Emphasized'), '<em>' . $this->t('Emphasized') . '</em>'),
diff --git a/core/modules/forum/forum.module b/core/modules/forum/forum.module
index 1b9b8f8..523bd87 100644
--- a/core/modules/forum/forum.module
+++ b/core/modules/forum/forum.module
@@ -674,7 +674,7 @@ function template_preprocess_forums(&$variables) {
         else {
           $new_replies = '';
           if ($topic->new_replies) {
-            $new_replies = '<br /><a href="' . $topic->new_url . '">' . $topic->new_text . '</a>';
+            $new_replies = '<br><a href="' . $topic->new_url . '">' . $topic->new_text . '</a>';
           }
 
           $row[] = array(
diff --git a/core/modules/forum/templates/forum-list.html.twig b/core/modules/forum/templates/forum-list.html.twig
index 5b41f6a..6fae175 100644
--- a/core/modules/forum/templates/forum-list.html.twig
+++ b/core/modules/forum/templates/forum-list.html.twig
@@ -68,7 +68,7 @@
         <td class="topics">
           {{ forum.num_topics }}
           {% if forum.new_topics == true %}
-            <br />
+            <br>
             <a href="{{ forum.new_url }}">{{ forum.new_text }}</a>
           {% endif %}
         </td>
diff --git a/core/modules/locale/locale.pages.inc b/core/modules/locale/locale.pages.inc
index c35e33a..9411fc0 100644
--- a/core/modules/locale/locale.pages.inc
+++ b/core/modules/locale/locale.pages.inc
@@ -286,12 +286,12 @@ function theme_locale_translate_edit_form_strings($variables) {
   foreach (Element::children($form) as $lid) {
     $string = $form[$lid];
     if ($string['plural']['#value']) {
-      $source = drupal_render($string['original_singular']) . '<br />' . drupal_render($string['original_plural']);
+      $source = drupal_render($string['original_singular']) . '<br>' . drupal_render($string['original_plural']);
     }
     else {
       $source = drupal_render($string['original']);
     }
-    $source .= empty($string['context']) ? '' : '<br /><small>' . t('In Context') . ':&nbsp;' . $string['context']['#value'] . '</small>';
+    $source .= empty($string['context']) ? '' : '<br><small>' . t('In Context') . ':&nbsp;' . $string['context']['#value'] . '</small>';
     $rows[] = array(
       array('data' => $source),
       array('data' => $string['translations']),
diff --git a/core/modules/simpletest/src/WebTestBase.php b/core/modules/simpletest/src/WebTestBase.php
index ec50d4d..509880a 100644
--- a/core/modules/simpletest/src/WebTestBase.php
+++ b/core/modules/simpletest/src/WebTestBase.php
@@ -1815,7 +1815,7 @@ protected function drupalPostAjaxForm($path, $edit, $triggering_element, $ajax_p
     }
 
     $verbose = 'AJAX POST request to: ' . $path;
-    $verbose .= '<br />AJAX controller path: ' . $ajax_path;
+    $verbose .= '<br>AJAX controller path: ' . $ajax_path;
     $verbose .= '<hr />Ending URL: ' . $this->getUrl();
     $verbose .= '<hr />' . $this->content;
 
diff --git a/core/modules/statistics/src/Plugin/Block/StatisticsPopularBlock.php b/core/modules/statistics/src/Plugin/Block/StatisticsPopularBlock.php
index 1a19761..d0c1722 100644
--- a/core/modules/statistics/src/Plugin/Block/StatisticsPopularBlock.php
+++ b/core/modules/statistics/src/Plugin/Block/StatisticsPopularBlock.php
@@ -122,17 +122,17 @@ public function build() {
 
     if ($this->day_list) {
       $content['top_day'] = $this->day_list;
-      $content['top_day']['#suffix'] = '<br />';
+      $content['top_day']['#suffix'] = '<br>';
     }
 
     if ($this->all_time_list) {
       $content['top_all'] = $this->all_time_list;
-      $content['top_all']['#suffix'] = '<br />';
+      $content['top_all']['#suffix'] = '<br>';
     }
 
     if ($this->last_list) {
       $content['top_last'] = $this->last_list;
-      $content['top_last']['#suffix'] = '<br />';
+      $content['top_last']['#suffix'] = '<br>';
     }
 
     return $content;
diff --git a/core/modules/statistics/statistics.module b/core/modules/statistics/statistics.module
index e5828c3..f34a43c 100644
--- a/core/modules/statistics/statistics.module
+++ b/core/modules/statistics/statistics.module
@@ -189,7 +189,7 @@ function _statistics_link($path, $width = 35) {
  */
 function _statistics_format_item($title, $path) {
   $path = ($path ? $path : '/');
-  $output  = ($title ? "$title<br />" : '');
+  $output  = ($title ? "$title<br>" : '');
   $output .= _statistics_link($path);
   return $output;
 }
diff --git a/core/modules/system/src/Tests/Form/ProgrammaticTest.php b/core/modules/system/src/Tests/Form/ProgrammaticTest.php
index a73f843..6571ddd 100644
--- a/core/modules/system/src/Tests/Form/ProgrammaticTest.php
+++ b/core/modules/system/src/Tests/Form/ProgrammaticTest.php
@@ -87,7 +87,7 @@ private function submitForm($values, $valid_input) {
       '%values' => print_r($values, TRUE),
       '%errors' => $valid_form ? t('None') : implode(' ', $errors),
     );
-    $this->assertTrue($valid_input == $valid_form, format_string('Input values: %values<br />Validation handler errors: %errors', $args));
+    $this->assertTrue($valid_input == $valid_form, format_string('Input values: %values<br>Validation handler errors: %errors', $args));
 
     // We check submitted values only if we have a valid input.
     if ($valid_input) {
diff --git a/core/modules/system/src/Tests/Mail/HtmlToTextTest.php b/core/modules/system/src/Tests/Mail/HtmlToTextTest.php
index e55e0563..bd2ad65 100644
--- a/core/modules/system/src/Tests/Mail/HtmlToTextTest.php
+++ b/core/modules/system/src/Tests/Mail/HtmlToTextTest.php
@@ -61,12 +61,12 @@ protected function assertHtmlToText($html, $text, $message, $allowed_tags = NULL
     $result = drupal_html_to_text($html, $allowed_tags);
     $pass = $this->assertEqual($result, $text, check_plain($message));
     $verbose = 'html = <pre>' . $this->stringToHtml($html)
-      . '</pre><br />' . 'result = <pre>' . $this->stringToHtml($result)
-      . '</pre><br />' . 'expected = <pre>' . $this->stringToHtml($text)
+      . '</pre><br>' . 'result = <pre>' . $this->stringToHtml($result)
+      . '</pre><br>' . 'expected = <pre>' . $this->stringToHtml($text)
       . '</pre>';
     $this->verbose($verbose);
     if (!$pass) {
-      $this->pass("Previous test verbose info:<br />$verbose");
+      $this->pass("Previous test verbose info:<br>$verbose");
     }
   }
 
diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index 6161819..817e4d7 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -313,7 +313,7 @@ function system_requirements($phase) {
     }
 
     $description .= ' ' . t('You can <a href="@cron">run cron manually</a>.', array('@cron' => url('admin/reports/status/run-cron')));
-    $description .= '<br />' . t('To run cron from outside the site, go to <a href="!cron">!cron</a>', array('!cron' => url('cron/' . \Drupal::state()->get('system.cron_key'), array('absolute' => TRUE))));
+    $description .= '<br>' . t('To run cron from outside the site, go to <a href="!cron">!cron</a>', array('!cron' => url('cron/' . \Drupal::state()->get('system.cron_key'), array('absolute' => TRUE))));
 
     $requirements['cron'] = array(
       'title' => t('Cron maintenance tasks'),
diff --git a/core/modules/system/tests/modules/batch_test/batch_test.callbacks.inc b/core/modules/system/tests/modules/batch_test/batch_test.callbacks.inc
index ca1ea6f..c8c3ef8 100644
--- a/core/modules/system/tests/modules/batch_test/batch_test.callbacks.inc
+++ b/core/modules/system/tests/modules/batch_test/batch_test.callbacks.inc
@@ -91,7 +91,7 @@ function _batch_test_finished_helper($batch_id, $success, $results, $operations)
   if (!$success) {
     // A fatal error occurred during the processing.
     $error_operation = reset($operations);
-    $messages[] = t('An error occurred while processing @op with arguments:<br />@args', array('@op' => $error_operation[0], '@args' => print_r($error_operation[1], TRUE)));
+    $messages[] = t('An error occurred while processing @op with arguments:<br>@args', array('@op' => $error_operation[0], '@args' => print_r($error_operation[1], TRUE)));
   }
 
   drupal_set_message(implode('<br>', $messages));
diff --git a/core/modules/system/tests/themes/test_theme/templates/theme-test-specific-suggestions--variant--foo.html.twig b/core/modules/system/tests/themes/test_theme/templates/theme-test-specific-suggestions--variant--foo.html.twig
index 7e0b485..826b43d 100644
--- a/core/modules/system/tests/themes/test_theme/templates/theme-test-specific-suggestions--variant--foo.html.twig
+++ b/core/modules/system/tests/themes/test_theme/templates/theme-test-specific-suggestions--variant--foo.html.twig
@@ -2,4 +2,4 @@
 Template overridden based on suggestion alter hook determined by the base hook.
 
 <p>Theme hook suggestions:
-{{ theme_hook_suggestions|join("<br />") }}</p>
+{{ theme_hook_suggestions|join("<br>") }}</p>
diff --git a/core/modules/system/tests/themes/test_theme/templates/theme-test-specific-suggestions--variant.html.twig b/core/modules/system/tests/themes/test_theme/templates/theme-test-specific-suggestions--variant.html.twig
index 655db4e..c70f600 100644
--- a/core/modules/system/tests/themes/test_theme/templates/theme-test-specific-suggestions--variant.html.twig
+++ b/core/modules/system/tests/themes/test_theme/templates/theme-test-specific-suggestions--variant.html.twig
@@ -2,4 +2,4 @@
 Template matching the specific theme call.
 
 <p>Theme hook suggestions:
-{{ theme_hook_suggestions|join("<br />") }}</p>
+{{ theme_hook_suggestions|join("<br>") }}</p>
diff --git a/core/modules/tracker/tracker.pages.inc b/core/modules/tracker/tracker.pages.inc
index 30c7915..1bbedaa 100644
--- a/core/modules/tracker/tracker.pages.inc
+++ b/core/modules/tracker/tracker.pages.inc
@@ -75,7 +75,7 @@ function tracker_page($account = NULL) {
         $comments = $node->comment_count;
 
         if ($new = comment_num_new($node->id(), 'node')) {
-          $comments .= '<br />';
+          $comments .= '<br>';
           $comments .= l(format_plural($new, '1 new', '@count new'), 'node/' . $node->id(), array('fragment' => 'new'));
         }
       }
diff --git a/core/modules/user/src/RegisterForm.php b/core/modules/user/src/RegisterForm.php
index 30f3018..20dcc70 100644
--- a/core/modules/user/src/RegisterForm.php
+++ b/core/modules/user/src/RegisterForm.php
@@ -143,7 +143,7 @@ public function save(array $form, array &$form_state) {
     // Administrator approval required.
     else {
       _user_mail_notify('register_pending_approval', $account);
-      drupal_set_message($this->t('Thank you for applying for an account. Your account is currently pending approval by the site administrator.<br />In the meantime, a welcome message with further instructions has been sent to your e-mail address.'));
+      drupal_set_message($this->t('Thank you for applying for an account. Your account is currently pending approval by the site administrator.<br>In the meantime, a welcome message with further instructions has been sent to your e-mail address.'));
       $form_state['redirect_route']['route_name'] = '<front>';
     }
   }
diff --git a/core/modules/views/src/Plugin/entity_reference/selection/ViewsSelection.php b/core/modules/views/src/Plugin/entity_reference/selection/ViewsSelection.php
index aa84db2..c52ae4d 100644
--- a/core/modules/views/src/Plugin/entity_reference/selection/ViewsSelection.php
+++ b/core/modules/views/src/Plugin/entity_reference/selection/ViewsSelection.php
@@ -89,7 +89,7 @@ public static function settingsForm(FieldDefinitionInterface $field_definition)
         '#required' => TRUE,
         '#options' => $options,
         '#default_value' => $default,
-        '#description' => '<p>' . t('Choose the view and display that select the entities that can be referenced.<br />Only views with a display of type "Entity Reference" are eligible.') . '</p>',
+        '#description' => '<p>' . t('Choose the view and display that select the entities that can be referenced.<br>Only views with a display of type "Entity Reference" are eligible.') . '</p>',
       );
 
       $default = !empty($view_settings['arguments']) ? implode(', ', $view_settings['arguments']) : '';