diff --git a/core/lib/Drupal/Core/Cache/Context/AccountPermissionsCacheContext.php b/core/lib/Drupal/Core/Cache/Context/AccountPermissionsCacheContext.php
index f6a412a..aeb4fea 100644
--- a/core/lib/Drupal/Core/Cache/Context/AccountPermissionsCacheContext.php
+++ b/core/lib/Drupal/Core/Cache/Context/AccountPermissionsCacheContext.php
@@ -16,12 +16,12 @@
  *
  * Cache context ID: 'user.permissions'.
  */
-class AccountPermissionsCacheContext extends UserCacheContext {
+class AccountPermissionsCacheContext extends UserCacheContextBase implements CacheContextInterface {
 
   /**
    * The permissions hash generator.
    *
-   * @var \Drupal\user\PermissionsHashInterface
+   * @var \Drupal\Core\Session\PermissionsHashGeneratorInterface
    */
   protected $permissionsHashGenerator;
 
@@ -30,7 +30,7 @@ class AccountPermissionsCacheContext extends UserCacheContext {
    *
    * @param \Drupal\Core\Session\AccountInterface $user
    *   The current user.
-   * @param \Drupal\user\PermissionsHashInterface $permissions_hash_generator
+   * @param \Drupal\Core\Session\PermissionsHashGeneratorInterface
    *   The permissions hash generator.
    */
   public function __construct(AccountInterface $user, PermissionsHashGeneratorInterface $permissions_hash_generator) {
diff --git a/core/lib/Drupal/Core/Cache/Context/CacheContextsManager.php b/core/lib/Drupal/Core/Cache/Context/CacheContextsManager.php
index 81c7e37..a0157f5 100644
--- a/core/lib/Drupal/Core/Cache/Context/CacheContextsManager.php
+++ b/core/lib/Drupal/Core/Cache/Context/CacheContextsManager.php
@@ -107,15 +107,13 @@ public function getLabels($include_calculated_cache_contexts = FALSE) {
    * @throws \InvalidArgumentException
    */
   public function convertTokensToKeys(array $context_tokens) {
+    $this->validateTokens($context_tokens);
     $cacheable_metadata = new CacheableMetadata();
     $optimized_tokens = $this->optimizeTokens($context_tokens);
     // Iterate over cache contexts that have been optimized away and get their
     // cacheable metadata.
     foreach (static::parseTokens(array_diff($context_tokens, $optimized_tokens)) as $context_token) {
       list($context_id, $parameter) = $context_token;
-      if (!in_array($context_id, $this->contexts)) {
-        throw new \InvalidArgumentException(SafeMarkup::format('"@context" is not a valid cache context ID.', ['@context' => $context_id]));
-      }
       $context = $this->getService($context_id);
       $cacheable_metadata = $cacheable_metadata->merge($context->getCacheableMetadata($parameter));
     }
@@ -124,9 +122,6 @@ public function convertTokensToKeys(array $context_tokens) {
     $keys = [];
     foreach (static::parseTokens($optimized_tokens) as $context) {
       list($context_id, $parameter) = $context;
-      if (!in_array($context_id, $this->contexts)) {
-        throw new \InvalidArgumentException(SafeMarkup::format('"@context" is not a valid cache context ID.', ['@context' => $context_id]));
-      }
       $keys[] = $this->getService($context_id)->getContext($parameter);
     }
 
diff --git a/core/lib/Drupal/Core/Cache/Context/CookiesCacheContext.php b/core/lib/Drupal/Core/Cache/Context/CookiesCacheContext.php
index 534d10c..bd5ab66 100644
--- a/core/lib/Drupal/Core/Cache/Context/CookiesCacheContext.php
+++ b/core/lib/Drupal/Core/Cache/Context/CookiesCacheContext.php
@@ -7,6 +7,8 @@
 
 namespace Drupal\Core\Cache\Context;
 
+use Drupal\Core\Cache\CacheableMetadata;
+
 /**
  * Defines the CookiesCacheContext service, for "per cookie" caching.
  *
@@ -35,4 +37,11 @@ public function getContext($cookie = NULL) {
     }
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheableMetadata($cookie = NULL) {
+    return new CacheableMetadata();
+  }
+
 }
diff --git a/core/lib/Drupal/Core/Cache/Context/HeadersCacheContext.php b/core/lib/Drupal/Core/Cache/Context/HeadersCacheContext.php
index 8286b36..8b4e450 100644
--- a/core/lib/Drupal/Core/Cache/Context/HeadersCacheContext.php
+++ b/core/lib/Drupal/Core/Cache/Context/HeadersCacheContext.php
@@ -7,6 +7,8 @@
 
 namespace Drupal\Core\Cache\Context;
 
+use Drupal\Core\Cache\CacheableMetadata;
+
 /**
  * Defines the HeadersCacheContext service, for "per header" caching.
  *
@@ -35,4 +37,11 @@ public function getContext($header = NULL) {
     }
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheableMetadata($header = NULL) {
+    return new CacheableMetadata();
+  }
+
 }
diff --git a/core/lib/Drupal/Core/Cache/Context/IpCacheContext.php b/core/lib/Drupal/Core/Cache/Context/IpCacheContext.php
index 9cc6713..aac2926 100644
--- a/core/lib/Drupal/Core/Cache/Context/IpCacheContext.php
+++ b/core/lib/Drupal/Core/Cache/Context/IpCacheContext.php
@@ -7,12 +7,14 @@
 
 namespace Drupal\Core\Cache\Context;
 
+use Drupal\Core\Cache\CacheableMetadata;
+
 /**
  * Defines the IpCacheContext service, for "per IP address" caching.
  *
  * Cache context ID: 'ip'.
  */
-class IpCacheContext extends RequestStackCacheContextBase {
+class IpCacheContext extends RequestStackCacheContextBase implements CacheContextInterface {
 
   /**
    * {@inheritdoc}
@@ -28,4 +30,11 @@ public function getContext() {
     return $this->requestStack->getCurrentRequest()->getClientIp();
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheableMetadata() {
+    return new CacheableMetadata();
+  }
+
 }
diff --git a/core/lib/Drupal/Core/Cache/Context/IsSuperUserCacheContext.php b/core/lib/Drupal/Core/Cache/Context/IsSuperUserCacheContext.php
index 1f30cf1..801de25 100644
--- a/core/lib/Drupal/Core/Cache/Context/IsSuperUserCacheContext.php
+++ b/core/lib/Drupal/Core/Cache/Context/IsSuperUserCacheContext.php
@@ -7,12 +7,14 @@
 
 namespace Drupal\Core\Cache\Context;
 
+use Drupal\Core\Cache\CacheableMetadata;
+
 /**
  * Defines the IsSuperUserCacheContext service, for "super user or not" caching.
  *
  * Cache context ID: 'user.is_super_user'.
  */
-class IsSuperUserCacheContext extends UserCacheContext {
+class IsSuperUserCacheContext extends UserCacheContextBase implements CacheContextInterface {
 
   /**
    * {@inheritdoc}
@@ -28,4 +30,11 @@ public function getContext() {
     return ((int) $this->user->id()) === 1 ? '1' : '0';
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheableMetadata($menu_name = NULL) {
+    return new CacheableMetadata();
+  }
+
 }
diff --git a/core/lib/Drupal/Core/Cache/Context/PagersCacheContext.php b/core/lib/Drupal/Core/Cache/Context/PagersCacheContext.php
index f53d464..dc6143b 100644
--- a/core/lib/Drupal/Core/Cache/Context/PagersCacheContext.php
+++ b/core/lib/Drupal/Core/Cache/Context/PagersCacheContext.php
@@ -7,6 +7,8 @@
 
 namespace Drupal\Core\Cache\Context;
 
+use Drupal\Core\Cache\CacheableMetadata;
+
 /**
  * Defines a cache context for "per page in a pager" caching.
  *
@@ -38,4 +40,11 @@ public function getContext($pager_id = NULL) {
     return 'pager.' . $pager_id . '.' . pager_find_page($pager_id);
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheableMetadata($pager_id = NULL) {
+    return new CacheableMetadata();
+  }
+
 }
diff --git a/core/lib/Drupal/Core/Cache/Context/QueryArgsCacheContext.php b/core/lib/Drupal/Core/Cache/Context/QueryArgsCacheContext.php
index faceb07..cab1da8 100644
--- a/core/lib/Drupal/Core/Cache/Context/QueryArgsCacheContext.php
+++ b/core/lib/Drupal/Core/Cache/Context/QueryArgsCacheContext.php
@@ -7,6 +7,8 @@
 
 namespace Drupal\Core\Cache\Context;
 
+use Drupal\Core\Cache\CacheableMetadata;
+
 /**
  * Defines the QueryArgsCacheContext service, for "per query args" caching.
  *
@@ -35,4 +37,11 @@ public function getContext($query_arg = NULL) {
     }
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheableMetadata($query_arg = NULL) {
+    return new CacheableMetadata();
+  }
+
 }
diff --git a/core/lib/Drupal/Core/Cache/Context/RequestFormatCacheContext.php b/core/lib/Drupal/Core/Cache/Context/RequestFormatCacheContext.php
index b6784f7..e8cb154 100644
--- a/core/lib/Drupal/Core/Cache/Context/RequestFormatCacheContext.php
+++ b/core/lib/Drupal/Core/Cache/Context/RequestFormatCacheContext.php
@@ -7,6 +7,8 @@
 
 namespace Drupal\Core\Cache\Context;
 
+use Drupal\Core\Cache\CacheableMetadata;
+
 /**
  * Defines the RequestFormatCacheContext service, for "per format" caching.
  *
@@ -28,4 +30,11 @@ public function getContext() {
     return $this->requestStack->getCurrentRequest()->getRequestFormat();
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheableMetadata() {
+    return new CacheableMetadata();
+  }
+
 }
diff --git a/core/lib/Drupal/Core/Cache/Context/RequestStackCacheContextBase.php b/core/lib/Drupal/Core/Cache/Context/RequestStackCacheContextBase.php
index f4c960f..d6adff2 100644
--- a/core/lib/Drupal/Core/Cache/Context/RequestStackCacheContextBase.php
+++ b/core/lib/Drupal/Core/Cache/Context/RequestStackCacheContextBase.php
@@ -7,13 +7,12 @@
 
 namespace Drupal\Core\Cache\Context;
 
-use Drupal\Core\Cache\CacheableMetadata;
 use Symfony\Component\HttpFoundation\RequestStack;
 
 /**
  * Defines a base class for cache contexts depending only on the request stack.
  */
-abstract class RequestStackCacheContextBase implements CacheContextInterface {
+abstract class RequestStackCacheContextBase {
 
   /**
    * The request stack.
@@ -32,11 +31,4 @@ public function __construct(RequestStack $request_stack) {
     $this->requestStack = $request_stack;
   }
 
-  /**
-   * {@inheritdoc}
-   */
-  public function getCacheableMetadata() {
-    return new CacheableMetadata();
-  }
-
 }
diff --git a/core/lib/Drupal/Core/Cache/Context/SiteCacheContext.php b/core/lib/Drupal/Core/Cache/Context/SiteCacheContext.php
index e4d28cb..539ba9d 100644
--- a/core/lib/Drupal/Core/Cache/Context/SiteCacheContext.php
+++ b/core/lib/Drupal/Core/Cache/Context/SiteCacheContext.php
@@ -7,6 +7,8 @@
 
 namespace Drupal\Core\Cache\Context;
 
+use Drupal\Core\Cache\CacheableMetadata;
+
 /**
  * Defines the SiteCacheContext service, for "per site" caching.
  *
@@ -20,7 +22,7 @@
  * @see \Symfony\Component\HttpFoundation\Request::getSchemeAndHttpHost()
  * @see \Symfony\Component\HttpFoundation\Request::getBaseUrl()
  */
-class SiteCacheContext extends RequestStackCacheContextBase {
+class SiteCacheContext extends RequestStackCacheContextBase implements CacheContextInterface {
 
   /**
    * {@inheritdoc}
@@ -37,4 +39,11 @@ public function getContext() {
     return $request->getSchemeAndHttpHost() . $request->getBaseUrl();
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheableMetadata() {
+    return new CacheableMetadata();
+  }
+
 }
diff --git a/core/lib/Drupal/Core/Cache/Context/UrlCacheContext.php b/core/lib/Drupal/Core/Cache/Context/UrlCacheContext.php
index c0b0453..f240128 100644
--- a/core/lib/Drupal/Core/Cache/Context/UrlCacheContext.php
+++ b/core/lib/Drupal/Core/Cache/Context/UrlCacheContext.php
@@ -7,12 +7,14 @@
 
 namespace Drupal\Core\Cache\Context;
 
+use Drupal\Core\Cache\CacheableMetadata;
+
 /**
  * Defines the UrlCacheContext service, for "per page" caching.
  *
  * Cache context ID: 'url'.
  */
-class UrlCacheContext extends RequestStackCacheContextBase {
+class UrlCacheContext extends RequestStackCacheContextBase implements CacheContextInterface {
 
   /**
    * {@inheritdoc}
@@ -28,4 +30,11 @@ public function getContext() {
     return $this->requestStack->getCurrentRequest()->getUri();
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheableMetadata() {
+    return new CacheableMetadata();
+  }
+
 }
diff --git a/core/lib/Drupal/Core/Cache/Context/UserCacheContext.php b/core/lib/Drupal/Core/Cache/Context/UserCacheContext.php
index 983f8a3..1a0357a 100644
--- a/core/lib/Drupal/Core/Cache/Context/UserCacheContext.php
+++ b/core/lib/Drupal/Core/Cache/Context/UserCacheContext.php
@@ -8,24 +8,13 @@
 namespace Drupal\Core\Cache\Context;
 
 use Drupal\Core\Cache\CacheableMetadata;
-use Drupal\Core\Session\AccountInterface;
 
 /**
  * Defines the UserCacheContext service, for "per user" caching.
  *
  * Cache context ID: 'user'.
  */
-class UserCacheContext implements CacheContextInterface {
-
-  /**
-   * Constructs a new UserCacheContext service.
-   *
-   * @param \Drupal\Core\Session\AccountInterface $user
-   *   The current user.
-   */
-  public function __construct(AccountInterface $user) {
-    $this->user = $user;
-  }
+class UserCacheContext extends UserCacheContextBase implements CacheContextInterface {
 
   /**
    * {@inheritdoc}
diff --git a/core/lib/Drupal/Core/Cache/Context/UserCacheContextBase.php b/core/lib/Drupal/Core/Cache/Context/UserCacheContextBase.php
new file mode 100644
index 0000000..4cad8da
--- /dev/null
+++ b/core/lib/Drupal/Core/Cache/Context/UserCacheContextBase.php
@@ -0,0 +1,34 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Cache\Context\UserCacheContextBase.
+ */
+
+namespace Drupal\Core\Cache\Context;
+
+use Drupal\Core\Session\AccountInterface;
+
+/**
+ * Base class for user based cache contexts.
+ */
+abstract class UserCacheContextBase implements CacheContextInterface {
+
+  /**
+   * The account object.
+   *
+   * @var \Drupal\Core\Session\AccountInterface
+   */
+  protected $user;
+
+  /**
+   * Constructs a new UserCacheContext service.
+   *
+   * @param \Drupal\Core\Session\AccountInterface $user
+   *   The current user.
+   */
+  public function __construct(AccountInterface $user) {
+    $this->user = $user;
+  }
+
+}
diff --git a/core/lib/Drupal/Core/Cache/Context/UserRolesCacheContext.php b/core/lib/Drupal/Core/Cache/Context/UserRolesCacheContext.php
index 4221f14..1181634 100644
--- a/core/lib/Drupal/Core/Cache/Context/UserRolesCacheContext.php
+++ b/core/lib/Drupal/Core/Cache/Context/UserRolesCacheContext.php
@@ -7,6 +7,8 @@
 
 namespace Drupal\Core\Cache\Context;
 
+use Drupal\Core\Cache\CacheableMetadata;
+
 /**
  * Defines the UserRolesCacheContext service, for "per role" caching.
  *
@@ -17,7 +19,7 @@
  * Calculated cache context ID: 'user.roles:%role', e.g. 'user.roles:anonymous'
  * (to vary by the presence/absence of a specific role).
  */
-class UserRolesCacheContext extends UserCacheContext implements CalculatedCacheContextInterface {
+class UserRolesCacheContext extends UserCacheContextBase implements CalculatedCacheContextInterface {
 
   /**
    * {@inheritdoc}
@@ -45,4 +47,11 @@ public function getContext($role = NULL) {
     }
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheableMetadata($role = NULL) {
+    return new CacheableMetadata();
+  }
+
 }
diff --git a/core/modules/node/src/Cache/NodeAccessGrantsCacheContext.php b/core/modules/node/src/Cache/NodeAccessGrantsCacheContext.php
index 10c09f4..d304bf7 100644
--- a/core/modules/node/src/Cache/NodeAccessGrantsCacheContext.php
+++ b/core/modules/node/src/Cache/NodeAccessGrantsCacheContext.php
@@ -9,7 +9,7 @@
 
 use Drupal\Core\Cache\CacheableMetadata;
 use Drupal\Core\Cache\Context\CalculatedCacheContextInterface;
-use Drupal\Core\Cache\Context\UserCacheContext;
+use Drupal\Core\Cache\Context\UserCacheContextBase;
 
 /**
  * Defines the node access view cache context service.
@@ -23,7 +23,7 @@
  * @see node_query_node_access_alter()
  * @ingroup node_access
  */
-class NodeAccessGrantsCacheContext extends UserCacheContext implements CalculatedCacheContextInterface {
+class NodeAccessGrantsCacheContext extends UserCacheContextBase implements CalculatedCacheContextInterface {
 
   /**
    * {@inheritdoc}