diff --git a/core/core.services.yml b/core/core.services.yml
index afccb31..ad6bbdd 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -9,7 +9,7 @@ parameters:
     auto_reload: null
     cache: true
   renderer.config:
-    required_cache_contexts: ['languages:language_interface', 'theme', 'user.permissions']
+    required_cache_contexts: ['languages:language_interface', 'theme', 'user.permissions', 'url.site']
     auto_placeholder_conditions:
       max-age: 0
       contexts: ['session', 'user']
diff --git a/core/modules/block/src/Tests/BlockViewBuilderTest.php b/core/modules/block/src/Tests/BlockViewBuilderTest.php
index 331db82..eb11a82 100644
--- a/core/modules/block/src/Tests/BlockViewBuilderTest.php
+++ b/core/modules/block/src/Tests/BlockViewBuilderTest.php
@@ -292,7 +292,7 @@ public function testBlockViewBuilderBuildAlter() {
    *   The expected max-age.
    */
   protected function assertBlockRenderedWithExpectedCacheability(array $expected_keys, array $expected_contexts, array $expected_tags, $expected_max_age) {
-    $required_cache_contexts = ['languages:' . LanguageInterface::TYPE_INTERFACE, 'theme', 'user.permissions'];
+    $required_cache_contexts = ['languages:' . LanguageInterface::TYPE_INTERFACE, 'theme', 'user.permissions', 'url.site'];
 
     // Check that the expected cacheability metadata is present in:
     // - the built render array;
diff --git a/sites/default/default.services.yml b/sites/default/default.services.yml
index 23f6483..979b6f0 100644
--- a/sites/default/default.services.yml
+++ b/sites/default/default.services.yml
@@ -82,8 +82,8 @@ parameters:
     # The Renderer will automatically associate these cache contexts with every
     # render array, hence varying every render array by these cache contexts.
     #
-    # @default ['languages:language_interface', 'theme', 'user.permissions']
-    required_cache_contexts: ['languages:language_interface', 'theme', 'user.permissions']
+    # @default ['languages:language_interface', 'theme', 'user.permissions', 'url.site']
+    required_cache_contexts: ['languages:language_interface', 'theme', 'user.permissions', 'url.site']
     # Renderer automatic placeholdering conditions:
     #
     # Drupal allows portions of the page to be automatically deferred when