diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index 03572a6..bfbc84c 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -252,7 +252,7 @@ function drupal_get_filename($type, $name, $filename = NULL) {
     }
     // If still unknown, create a user-level error message.
     if (!isset($files[$type][$name])) {
-      trigger_error(SafeMarkup::format('The following @type is missing from the file system: @name', array('@type' => $type, '@name' => $name)), E_USER_WARNING);
+      trigger_error("The following $type is missing from the file system: $name", E_USER_WARNING);
     }
   }
 
diff --git a/core/lib/Drupal/Core/Config/PreExistingConfigException.php b/core/lib/Drupal/Core/Config/PreExistingConfigException.php
index 533d781..b60887b 100644
--- a/core/lib/Drupal/Core/Config/PreExistingConfigException.php
+++ b/core/lib/Drupal/Core/Config/PreExistingConfigException.php
@@ -7,8 +7,6 @@
 
 namespace Drupal\Core\Config;
 
-use Drupal\Component\Utility\SafeMarkup;
-
 /**
  * An exception thrown if configuration with the same name already exists.
  */
@@ -61,7 +59,7 @@ public function getExtension() {
    * @return \Drupal\Core\Config\PreExistingConfigException
    */
   public static function create($extension, array $config_objects) {
-    $message = SafeMarkup::format('Configuration objects (@config_names) provided by @extension already exist in active configuration',
+    $message = strtr('Configuration objects (@config_names) provided by @extension already exist in active configuration',
       array(
         '@config_names' => implode(', ', static::flattenConfigObjects($config_objects)),
         '@extension' => $extension
diff --git a/core/lib/Drupal/Core/Config/Testing/ConfigSchemaChecker.php b/core/lib/Drupal/Core/Config/Testing/ConfigSchemaChecker.php
index 4c01e13..d7a9888 100644
--- a/core/lib/Drupal/Core/Config/Testing/ConfigSchemaChecker.php
+++ b/core/lib/Drupal/Core/Config/Testing/ConfigSchemaChecker.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\Core\Config\Testing;
 
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Config\ConfigCrudEvent;
 use Drupal\Core\Config\ConfigEvents;
 use Drupal\Core\Config\Schema\SchemaCheckTrait;
@@ -93,7 +92,7 @@ public function onConfigSave(ConfigCrudEvent $event) {
       elseif (is_array($errors)) {
         $text_errors = [];
         foreach ($errors as $key => $error) {
-          $text_errors[] = SafeMarkup::format('@key @error', array('@key' => $key, '@error' => $error));
+          $text_errors[] = $key . ' ' .$error;
         }
         throw new SchemaIncompleteException("Schema errors for $name with the following errors: " . implode(', ', $text_errors));
       }
diff --git a/core/lib/Drupal/Core/Config/UnmetDependenciesException.php b/core/lib/Drupal/Core/Config/UnmetDependenciesException.php
index 22f1bde..c8c7e4f 100644
--- a/core/lib/Drupal/Core/Config/UnmetDependenciesException.php
+++ b/core/lib/Drupal/Core/Config/UnmetDependenciesException.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\Core\Config;
 
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\StringTranslation\TranslationInterface;
 
 /**
@@ -80,7 +79,7 @@ public function getTranslatedMessage(TranslationInterface $string_translation, $
    * @return \Drupal\Core\Config\PreExistingConfigException
    */
   public static function create($extension, array $config_objects) {
-    $message = SafeMarkup::format('Configuration objects (@config_names) provided by @extension have unmet dependencies',
+    $message = strtr('Configuration objects (@config_names) provided by @extension have unmet dependencies',
       array(
         '@config_names' => implode(', ', $config_objects),
         '@extension' => $extension
diff --git a/core/lib/Drupal/Core/Entity/ContentEntityBase.php b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
index f2c8436..79c75e5 100644
--- a/core/lib/Drupal/Core/Entity/ContentEntityBase.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\Core\Entity;
 
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Entity\Plugin\DataType\EntityReference;
 use Drupal\Core\Language\Language;
 use Drupal\Core\Language\LanguageInterface;
@@ -687,8 +686,7 @@ public function onChange($name) {
           // Update the default internal language cache.
           $this->setDefaultLangcode();
           if (isset($this->translations[$this->defaultLangcode])) {
-            $message = SafeMarkup::format('A translation already exists for the specified language (@langcode).', array('@langcode' => $this->defaultLangcode));
-            throw new \InvalidArgumentException($message);
+            throw new \InvalidArgumentException("A translation already exists for the specified language ({$this->defaultLangcode}).");
           }
           $this->updateFieldLangcodes($this->defaultLangcode);
         }
@@ -698,8 +696,7 @@ public function onChange($name) {
           $items = $this->get($this->langcodeKey);
           if ($items->value != $this->activeLangcode) {
             $items->setValue($this->activeLangcode, FALSE);
-            $message = SafeMarkup::format('The translation language cannot be changed (@langcode).', array('@langcode' => $this->activeLangcode));
-            throw new \LogicException($message);
+            throw new \LogicException("The translation language cannot be changed ({$this->activeLangcode}).");
           }
         }
         break;
@@ -709,8 +706,7 @@ public function onChange($name) {
         //   read-only. See https://www.drupal.org/node/2443991.
         if (isset($this->values[$this->defaultLangcodeKey]) && $this->get($this->defaultLangcodeKey)->value != $this->isDefaultTranslation()) {
           $this->get($this->defaultLangcodeKey)->setValue($this->isDefaultTranslation(), FALSE);
-          $message = SafeMarkup::format('The default translation flag cannot be changed (@langcode).', array('@langcode' => $this->activeLangcode));
-          throw new \LogicException($message);
+          throw new \LogicException("The default translation flag cannot be changed ({$this->activeLangcode}).");
         }
         break;
     }
diff --git a/core/lib/Drupal/Core/Entity/Plugin/DataType/EntityAdapter.php b/core/lib/Drupal/Core/Entity/Plugin/DataType/EntityAdapter.php
index 054d101..5dc1d2c 100644
--- a/core/lib/Drupal/Core/Entity/Plugin/DataType/EntityAdapter.php
+++ b/core/lib/Drupal/Core/Entity/Plugin/DataType/EntityAdapter.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\Core\Entity\Plugin\DataType;
 
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Entity\FieldableEntityInterface;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Entity\TypedData\EntityDataDefinition;
@@ -114,7 +113,7 @@ public function set($property_name, $value, $notify = TRUE) {
    */
   public function getProperties($include_computed = FALSE) {
     if (!isset($this->entity)) {
-      throw new MissingDataException(SafeMarkup::format('Unable to get properties as no entity has been provided.'));
+      throw new MissingDataException('Unable to get properties as no entity has been provided.');
     }
     if (!$this->entity instanceof FieldableEntityInterface) {
       // @todo: Add support for config entities in
diff --git a/core/lib/Drupal/Core/Extension/InfoParser.php b/core/lib/Drupal/Core/Extension/InfoParser.php
index 0bc9676..0b7f407 100644
--- a/core/lib/Drupal/Core/Extension/InfoParser.php
+++ b/core/lib/Drupal/Core/Extension/InfoParser.php
@@ -9,7 +9,6 @@
 
 use Drupal\Component\Serialization\Yaml;
 use Drupal\Component\Serialization\Exception\InvalidDataTypeException;
-use Drupal\Component\Utility\SafeMarkup;
 
 /**
  * Parses extension .info.yml files.
@@ -36,13 +35,11 @@ public function parse($filename) {
           static::$parsedInfos[$filename] = Yaml::decode(file_get_contents($filename));
         }
         catch (InvalidDataTypeException $e) {
-          $message = SafeMarkup::format("Unable to parse !file: !error", array('!file' => $filename, '!error' => $e->getMessage()));
-          throw new InfoParserException($message);
+          throw new InfoParserException("Unable to parse $filename: " . $e->getMessage());
         }
         $missing_keys = array_diff($this->getRequiredKeys(), array_keys(static::$parsedInfos[$filename]));
         if (!empty($missing_keys)) {
-          $message = SafeMarkup::format('Missing required keys (!missing_keys) in !file.', array('!missing_keys' => implode(', ', $missing_keys), '!file' => $filename));
-          throw new InfoParserException($message);
+          throw new InfoParserException('Missing required keys (' . implode(', ', $missing_keys) . ") in $filename.");
         }
         if (isset(static::$parsedInfos[$filename]['version']) && static::$parsedInfos[$filename]['version'] === 'VERSION') {
           static::$parsedInfos[$filename]['version'] = \Drupal::VERSION;
diff --git a/core/lib/Drupal/Core/ImageToolkit/ImageToolkitOperationManager.php b/core/lib/Drupal/Core/ImageToolkit/ImageToolkitOperationManager.php
index 1bc0999..2f68d73 100644
--- a/core/lib/Drupal/Core/ImageToolkit/ImageToolkitOperationManager.php
+++ b/core/lib/Drupal/Core/ImageToolkit/ImageToolkitOperationManager.php
@@ -12,7 +12,6 @@
 use Drupal\Core\Plugin\DefaultPluginManager;
 use Drupal\Component\Plugin\Exception\PluginNotFoundException;
 use Drupal\Component\Plugin\Factory\DefaultFactory;
-use Drupal\Component\Utility\SafeMarkup;
 use Psr\Log\LoggerInterface;
 
 /**
@@ -77,8 +76,7 @@ function ($definition) use ($toolkit_id, $operation) {
     );
 
     if (!$definitions) {
-      $message = SafeMarkup::format("No image operation plugin for '@toolkit' toolkit and '@operation' operation.", array('@toolkit' => $toolkit_id, '@operation' => $operation));
-      throw new PluginNotFoundException($toolkit_id . '.' . $operation, $message);
+      throw new PluginNotFoundException($toolkit_id . '.' . $operation, "No image operation plugin for '$toolkit_id' toolkit and '$operation' operation.");
     }
     else {
       // Pickup the first plugin found.
diff --git a/core/lib/Drupal/Core/Render/Element.php b/core/lib/Drupal/Core/Render/Element.php
index afc7695..70f34b1 100644
--- a/core/lib/Drupal/Core/Render/Element.php
+++ b/core/lib/Drupal/Core/Render/Element.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\Core\Render;
 
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Access\AccessResultInterface;
 
 /**
@@ -99,7 +98,7 @@ public static function children(array &$elements, $sort = FALSE) {
         // Only trigger an error if the value is not null.
         // @see https://www.drupal.org/node/1283892
         elseif (isset($value)) {
-          trigger_error(SafeMarkup::format('"@key" is an invalid render array key', array('@key' => $key)), E_USER_ERROR);
+          trigger_error("'$key' is an invalid render array key", E_USER_ERROR);
         }
       }
       $i++;
diff --git a/core/modules/views/src/ViewExecutable.php b/core/modules/views/src/ViewExecutable.php
index 774e63c..69add80 100644
--- a/core/modules/views/src/ViewExecutable.php
+++ b/core/modules/views/src/ViewExecutable.php
@@ -756,7 +756,7 @@ public function setDisplay($display_id = NULL) {
 
     // Ensure the requested display exists.
     if (!$this->displayHandlers->has($display_id)) {
-      debug(format_string('setDisplay() called with invalid display ID "@display".', array('@display' => $display_id)));
+      debug("setDisplay() called with invalid display ID '$display_id'.");
       return FALSE;
     }
 
diff --git a/core/tests/Drupal/Tests/Core/Render/ElementTest.php b/core/tests/Drupal/Tests/Core/Render/ElementTest.php
index 4149222..e32a995 100644
--- a/core/tests/Drupal/Tests/Core/Render/ElementTest.php
+++ b/core/tests/Drupal/Tests/Core/Render/ElementTest.php
@@ -108,7 +108,7 @@ public function testChildren() {
    * Tests the children() method with an invalid key.
    *
    * @expectedException \PHPUnit_Framework_Error
-   * @expectedExceptionMessage "foo" is an invalid render array key
+   * @expectedExceptionMessage 'foo' is an invalid render array key
    */
   public function testInvalidChildren() {
     $element = array(