diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorCronTest.php b/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorCronTest.php
index 0966937..47617a0 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorCronTest.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorCronTest.php
@@ -22,7 +22,7 @@ public static function getInfo() {
   public function testCron() {
     // Create feed and test basic updating on cron.
     global $base_url;
-    $key = config('system.cron')->get('key');
+    $key = state()->get('system.cron_key');
     $this->createSampleNodes();
     $feed = $this->createFeed();
     $this->cronRun();
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
index ecf2861..48887a6 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
@@ -1430,7 +1430,7 @@ protected function drupalPostAJAX($path, $edit, $triggering_element, $ajax_path
    * Runs cron in the Drupal installed by Simpletest.
    */
   protected function cronRun() {
-    $this->drupalGet('cron/' . config('system.cron')->get('key'));
+    $this->drupalGet('cron/' . state()->get('system.cron_key'));
   }
 
   /**
diff --git a/core/modules/system/config/system.cron.yml b/core/modules/system/config/system.cron.yml
index b9a5096..aa41f1b 100644
--- a/core/modules/system/config/system.cron.yml
+++ b/core/modules/system/config/system.cron.yml
@@ -1,4 +1,3 @@
-key: ''
 threshold:
   autorun: '10800'
   requirements_warning: '172800'
diff --git a/core/modules/system/lib/Drupal/system/Tests/System/CronRunTest.php b/core/modules/system/lib/Drupal/system/Tests/System/CronRunTest.php
index ebdb103..1e8662c 100644
--- a/core/modules/system/lib/Drupal/system/Tests/System/CronRunTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/System/CronRunTest.php
@@ -42,7 +42,7 @@ function testCronRun() {
     $this->assertResponse(403);
 
     // Run cron anonymously with the valid cron key.
-    $key = config('system.cron')->get('key');
+    $key = state()->get('system.cron_key');
     $this->drupalGet('cron/' . $key);
     $this->assertResponse(204);
   }
diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index 8127e00..e0772ad 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -294,7 +294,7 @@ function system_requirements($phase) {
     }
 
     $description .= ' ' . $t('You can <a href="@cron">run cron manually</a>.', array('@cron' => url('admin/reports/status/run-cron')));
-    $description .= '<br />' . $t('To run cron from outside the site, go to <a href="!cron">!cron</a>', array('!cron' => url('cron/' . $cron_config->get('key'))));
+    $description .= '<br />' . $t('To run cron from outside the site, go to <a href="!cron">!cron</a>', array('!cron' => url('cron/' . state()->get('system.cron_key'))));
 
     $requirements['cron'] = array(
       'title' => $t('Cron maintenance tasks'),
@@ -512,11 +512,9 @@ function system_install() {
   variable_set('theme_default', 'stark');
   config_install_default_config('theme', 'stark');
 
-  // Populate the cron key variable.
+  // Populate the cron key state variable.
   $cron_key = drupal_hash_base64(drupal_random_bytes(55));
-  config('system.cron')
-    ->set('key', $cron_key)
-    ->save();
+  state()->set('system.cron_key', $cron_key);
 }
 
 /**
@@ -1750,17 +1748,21 @@ function system_update_8008() {
 }
 
 /**
- * Moves cron system settings from variable to config.
+ * Moves cron system settings from variable to config/state.
  *
  * @ingroup config_upgrade
  */
 function system_update_8009() {
   update_variables_to_config('system.cron', array(
-    'cron_key' => 'key',
     'cron_safe_threshold' => 'threshold.autorun',
     'cron_threshold_warning' => 'threshold.requirements_warning',
     'cron_threshold_error' => 'threshold.requirements_error',
   ));
+
+  if ($cron_key = update_variable_get('cron_key', FALSE)) {
+    state()->set('system.cron_key', $cron_key);
+  }
+  update_variable_del('cron_key');
 }
 
 /**
diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index ea3dadc..8cf57eb 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -1101,7 +1101,7 @@ function system_cron_page() {
  * @see system_cron_page().
  */
 function system_cron_access($key) {
-  if ($key != config('system.cron')->get('key')) {
+  if ($key != state()->get('system.cron_key')) {
     watchdog('cron', 'Cron could not run because an invalid key was used.', array(), WATCHDOG_NOTICE);
     return FALSE;
   }