core/modules/book/src/Plugin/Block/BookNavigationBlock.php |  4 +---
 core/modules/system/src/Plugin/Block/SystemMenuBlock.php   | 13 +++++++++++--
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/core/modules/book/src/Plugin/Block/BookNavigationBlock.php b/core/modules/book/src/Plugin/Block/BookNavigationBlock.php
index 30153be..ffcba6f 100644
--- a/core/modules/book/src/Plugin/Block/BookNavigationBlock.php
+++ b/core/modules/book/src/Plugin/Block/BookNavigationBlock.php
@@ -182,10 +182,8 @@ public function build() {
    * {@inheritdoc}
    */
   public function getCacheContexts() {
-    // The "Book navigation" block must be cached per role and book navigation
-    // context.
+    // The "Book navigation" block varies by the book navigation cache context.
     return [
-      'user.roles',
       'route.book_navigation',
     ];
   }
diff --git a/core/modules/system/src/Plugin/Block/SystemMenuBlock.php b/core/modules/system/src/Plugin/Block/SystemMenuBlock.php
index 4a6a2ea..3bb49bb 100644
--- a/core/modules/system/src/Plugin/Block/SystemMenuBlock.php
+++ b/core/modules/system/src/Plugin/Block/SystemMenuBlock.php
@@ -187,12 +187,21 @@ public function getCacheTags() {
    * {@inheritdoc}
    */
   public function getCacheContexts() {
-    // Menu blocks must be cached per role and per active trail.
+    // Menu blocks must be cached per active menu trail.
     $menu_name = $this->getDerivativeId();
     return [
-      'user.roles',
       'route.menu_active_trails:' . $menu_name,
     ];
   }
 
+  /**
+   * {@inheritdoc}
+   *
+   * @todo Make cacheable as part of https://drupal.org/node/1805054
+   */
+  public function getCacheMaxAge() {
+    return 0;
+  }
+
+
 }