diff --git a/core/lib/Drupal/Core/Cache/Cache.php b/core/lib/Drupal/Core/Cache/Cache.php
index 718f616..1521d4b 100644
--- a/core/lib/Drupal/Core/Cache/Cache.php
+++ b/core/lib/Drupal/Core/Cache/Cache.php
@@ -81,7 +81,7 @@ public static function validateTags(array $tags) {
    *   A prefix string.
    * @param array $suffixes
    *   An array of suffixes. Will be cast to strings.
-   * @param $glue
+   * @param string $glue
    *   A string to be used as glue for concatenation. Defaults to a colon.
    *
    * @return string[]
diff --git a/core/modules/contact/src/Access/ContactPageAccess.php b/core/modules/contact/src/Access/ContactPageAccess.php
index 7b5ad48..97d6b06 100644
--- a/core/modules/contact/src/Access/ContactPageAccess.php
+++ b/core/modules/contact/src/Access/ContactPageAccess.php
@@ -95,7 +95,7 @@ public function access(UserInterface $user, AccountInterface $account) {
     // configured default is disabled.
     $contact_settings = $this->configFactory->get('contact.settings');
     $access->cacheUntilConfigurationChanges($contact_settings);
-    if (!$contact_settings->get('user_default_enabled')) {
+    if (!isset($account_data) && !$contact_settings->get('user_default_enabled')) {
       return $access;
     }
 
diff --git a/core/modules/system/src/EventSubscriber/ThemeSettingsCacheTag.php b/core/modules/system/src/EventSubscriber/ThemeSettingsCacheTag.php
index 844df16..a6a6b7c 100644
--- a/core/modules/system/src/EventSubscriber/ThemeSettingsCacheTag.php
+++ b/core/modules/system/src/EventSubscriber/ThemeSettingsCacheTag.php
@@ -29,7 +29,7 @@ class ThemeSettingsCacheTag implements EventSubscriberInterface {
    * Constructs a ThemeSettingsCacheTag object.
    *
    * @param \Drupal\Core\Extension\ThemeHandlerInterface $theme_handler
-   *   The theme handler
+   *   The theme handler.
    */
   public function __construct(ThemeHandlerInterface $theme_handler) {
     $this->themeHandler = $theme_handler;
@@ -47,11 +47,12 @@ public function onSave(ConfigCrudEvent $event) {
       Cache::invalidateTags(['rendered']);
     }
 
-    // Theme-specific settings.
-    $matches = [];
-    if (preg_match('/(.*)\.settings$/', $event->getConfig()->getName(), $matches)) {
-      if (in_array($matches[1], array_keys($this->themeHandler->listInfo()))) {
+    // Theme-specific settings, check if this matches a theme settings
+    // configuration object, in that case, clear the rendered cache tag.
+    foreach (array_keys($this->themeHandler->listInfo()) as $theme_name) {
+      if ($theme_name == $event->getConfig()->getName()) {
         Cache::invalidateTags(['rendered']);
+        break;
       }
     }
   }
diff --git a/core/tests/Drupal/Tests/Core/Access/AccessResultTest.php b/core/tests/Drupal/Tests/Core/Access/AccessResultTest.php
index add45c2..da5651c 100644
--- a/core/tests/Drupal/Tests/Core/Access/AccessResultTest.php
+++ b/core/tests/Drupal/Tests/Core/Access/AccessResultTest.php
@@ -449,7 +449,7 @@ public function testCacheTags() {
     $verify($b, $tags);
     $this->assertEquals($a, $b);
 
-    // ::cacheUntilEntityChanges() convenience method.
+    // ::cacheUntilConfigurationChanges() convenience method.
     $configuration = $this->getMock('\Drupal\Core\Config\ConfigBase');
     $configuration->expects($this->any())
       ->method('getCacheTags')
diff --git a/core/tests/Drupal/Tests/Core/Cache/CacheTest.php b/core/tests/Drupal/Tests/Core/Cache/CacheTest.php
index a425572..1ef83a0 100644
--- a/core/tests/Drupal/Tests/Core/Cache/CacheTest.php
+++ b/core/tests/Drupal/Tests/Core/Cache/CacheTest.php
@@ -105,6 +105,8 @@ public function buildTagsProvider() {
       ['node', [5 => NULL], ['node:']],
       ['node', ['a' => NULL], ['node:']],
       ['node', ['a' => TRUE], ['node:1']],
+      // Test the $glue parameter.
+      ['config:system.menu', ['menu_name'], ['config:system.menu.menu_name'], '.'],
     ];
   }
 
@@ -113,8 +115,8 @@ public function buildTagsProvider() {
    *
    * @dataProvider buildTagsProvider
    */
-  public function testBuildTags($prefix, array $suffixes, array $expected) {
-    $this->assertEquals($expected, Cache::buildTags($prefix, $suffixes));
+  public function testBuildTags($prefix, array $suffixes, array $expected, $glue = ':') {
+    $this->assertEquals($expected, Cache::buildTags($prefix, $suffixes, $glue));
   }
 
   /**