diff --git a/core/modules/block/block.install b/core/modules/block/block.install
index 7010f59..fba7c5d 100644
--- a/core/modules/block/block.install
+++ b/core/modules/block/block.install
@@ -16,3 +16,129 @@ function block_install() {
   // invalidate all cached HTML output.
   Cache::invalidateTags(['rendered']);
 }
+
+/**
+ * @addtogroup updates-8.0.0-beta
+ * @{
+ */
+
+/**
+ * Update block visibility context mapping.
+ */
+function block_update_8001() {
+  // This update function updates blocks for the change from
+  // https://www.drupal.org/node/2354889
+
+  // Core visibility context plugins are updated automatically; blocks with
+  // unknown plugins are disabled and their previous visibility settings are
+  // saved in key value storage; see change record
+  // https://www.drupal.org/node/2527840 for more explanation.
+
+  // These are all the contexts that Drupal core provides.
+  $context_service_id_map = [
+    'language' => 'language.current_language_context',
+    'node.node' => '@node.node_route_context:node',
+    'user.current_user' => '@user.current_user_context:current_user',
+  ];
+
+  foreach (array_keys(\Drupal::languageManager()->getDefinedLanguageTypesInfo()) as $language_type_id) {
+    $context_service_id_map['language.' . $language_type_id] = '@language.current_language_context:' . $language_type_id;
+  }
+
+  // Contributed modules should leverage hook_update_dependencies() in order to
+  // be executed before block_update_8002(), so they can update their context
+  // mappings, if wanted.
+  $config_factory = \Drupal::configFactory();
+  $backup_values = $update_backup = [];
+
+  foreach ($config_factory->listAll('block.block.') as $block_config_name) {
+    $block = $config_factory->getEditable($block_config_name);
+    if ($visibility = $block->get('visibility')) {
+      foreach ($visibility as $condition_plugin_id => &$condition) {
+        foreach ($condition['context_mapping'] as $key => $context) {
+          if (!isset($context_service_id_map[$context])) {
+            // Remove the visibility condition for unknown context mapping
+            // entries, so the update process itself runs through and users can
+            // fix their block placements manually OR alternatively contributed
+            // modules can run their own update functions to update mappings
+            // that they provide.
+            $backup_values[$context][] = $condition_plugin_id;
+            unset($visibility[$condition_plugin_id]);
+            continue;
+          }
+          // We replace the previous format of "{$context_id}"
+          // with "@{$service_id}:{$unqualified_context_id}".
+          $condition['context_mapping'][$key] = $context_service_id_map[$context];
+        }
+      }
+      $block->set('visibility', $visibility);
+
+      if ($backup_values) {
+        // We not only store the missing context mappings but also the previous
+        // block status, in order to allow contributed and custom modules to do
+        // their own updates.
+        $update_backup[$block->get('id')] = [
+          'missing_context_ids' => $backup_values,
+          'status' => $block->get('status')
+        ];
+      }
+    }
+
+    // Mark the resulting configuration as trusted data. This avoids issues with
+    // future schema changes.
+    $block->save(TRUE);
+  }
+
+  if ($update_backup) {
+    \Drupal::keyValue('update_backup')->set('block_update_8001', $update_backup);
+  }
+
+  return t('Block context IDs updated.');
+}
+
+/**
+ * Disable all blocks with missing context IDs in block_update_8001().
+ */
+function block_update_8002() {
+  $block_update_8001 = \Drupal::keyValue('update_backup')->get('block_update_8001', []);
+
+  $block_ids = array_keys($block_update_8001);
+  $config_factory = \Drupal::configFactory();
+  /** @var \Drupal\Core\Config\Config[] $blocks */
+  $blocks = [];
+  foreach ($block_ids as $block_id) {
+    $blocks[$block_id] = $block = $config_factory->getEditable('block.block.' . $block_id);
+    // This block will have an invalid context mapping service and must be
+    // disabled in order to prevent information disclosure.
+    $block->set('status', FALSE);
+    $block->save(TRUE);
+  }
+
+  // Provides a list of plugin labels, keyed by plugin ID.
+  $condition_plugin_id_label_map = array_column(\Drupal::service('plugin.manager.condition')->getDefinitions(), 'label', 'id');
+
+  // Override with the UI labels we are aware of. Sadly they are not machine
+  // accessible, see
+  // \Drupal\node\Plugin\Condition\NodeType::buildConfigurationForm().
+  $condition_plugin_id_label_map['node_type'] = t('Content types');
+  $condition_plugin_id_label_map['request_path'] = t('Pages');
+  $condition_plugin_id_label_map['user_role'] = t('Roles');
+
+  if (count($block_ids) > 0) {
+    $message = t('Encountered an unknown context mapping key coming probably from a contributed or custom module: One or more mappings could not be updated. Please manually review your visibility settings for the following blocks, which are disabled now:');
+    $message .= '<ul>';
+    foreach ($blocks as $disabled_block_id => $disabled_block) {
+      $message .= '<li>' . t('@label (Visibility: @plugin_ids)', array(
+            '@label' => $disabled_block->get('settings.label'),
+            '@plugin_ids' => implode(', ', array_intersect_key($condition_plugin_id_label_map, array_flip(array_keys($block_update_8001[$disabled_block_id]['missing_context_ids']))))
+          )) . '</li>';
+    }
+    $message .= '</ul>';
+
+    return $message;
+  }
+}
+
+/**
+ * @} End of "addtogroup updates-8.0.0-beta".
+ */
diff --git a/core/modules/block/src/Tests/Update/BlockContextMappingUpdateTest.php b/core/modules/block/src/Tests/Update/BlockContextMappingUpdateTest.php
new file mode 100644
index 0000000..da03fa0
--- /dev/null
+++ b/core/modules/block/src/Tests/Update/BlockContextMappingUpdateTest.php
@@ -0,0 +1,110 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\block\Tests\Update\BlockContextMappingUpdateTest.
+ */
+
+namespace Drupal\block\Tests\Update;
+
+use Drupal\block\Entity\Block;
+use Drupal\node\Entity\Node;
+use Drupal\system\Tests\Update\UpdatePathTestBase;
+
+/**
+ * Tests the upgrade path for block context mapping renames.
+ *
+ * @see https://www.drupal.org/node/2354889
+ *
+ * @group Update
+ */
+class BlockContextMappingUpdateTest extends UpdatePathTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['block_test', 'language'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    $this->databaseDumpFiles = [
+      __DIR__ . '/../../../../system/tests/fixtures/update/drupal-8.bare.standard.php.gz',
+      __DIR__ . '/../../../../system/tests/fixtures/update/drupal-8.block-context-manager-2354889.php',
+    ];
+    parent::setUp();
+  }
+
+  /**
+   * Tests that block context mapping is updated properly.
+   */
+  public function testUpdateHookN() {
+    $this->runUpdates();
+    $this->assertRaw('Encountered an unknown context mapping key coming probably from a contributed or custom module: One or more mappings could not be updated. Please manually review your visibility settings for the following blocks, which are disabled now:<ul><li>User login (Visibility: Baloney spam)</li></ul>');
+
+    // Disable maintenance mode.
+    \Drupal::state()->set('system.maintenance_mode', FALSE);
+
+    // We finished updating so we can login the user now.
+    $this->drupalLogin($this->rootUser);
+
+    // The block that we are testing has the following visibility rules:
+    // - only visible on node pages
+    // - only visible to authenticated users.
+    $block_title = 'Test for 2354889';
+
+    // Create two nodes, a page and an article.
+    $page = Node::create([
+      'type' => 'page',
+      'title' => 'Page node',
+    ]);
+    $page->save();
+
+    $article = Node::create([
+      'type' => 'article',
+      'title' => 'Article node',
+    ]);
+    $article->save();
+
+    // Check that the block appears only on Page nodes for authenticated users.
+    $this->drupalGet('node/' . $page->id());
+    $this->assertRaw($block_title, 'Test block is visible on a Page node as an authenticated user.');
+
+    $this->drupalGet('node/' . $article->id());
+    $this->assertNoRaw($block_title, 'Test block is not visible on a Article node as an authenticated user.');
+
+    $this->drupalLogout();
+
+    // Check that the block does not appear on any page for anonymous users.
+    $this->drupalGet('node/' . $page->id());
+    $this->assertNoRaw($block_title, 'Test block is not visible on a Page node as an anonymous user.');
+
+    $this->drupalGet('node/' . $article->id());
+    $this->assertNoRaw($block_title, 'Test block is not visible on a Article node as an anonymous user.');
+
+    // Ensure that all the context mappings got updated properly.
+    $block = Block::load('testfor2354889');
+    $visibility = $block->get('visibility');
+    $this->assertEqual('@node.node_route_context:node', $visibility['node_type']['context_mapping']['node']);
+    $this->assertEqual('@user.current_user_context:current_user', $visibility['user_role']['context_mapping']['user']);
+    $this->assertEqual('@language.current_language_context:language_interface', $visibility['language']['context_mapping']['language']);
+
+    // Check that a block with invalid context is being disabled and that it can
+    // still be edited afterward.
+    $disabled_block = Block::load('thirdtestfor2354889');
+    $this->assertFalse($disabled_block->status(), 'Block with invalid context is disabled');
+
+    $this->assertEqual(['thirdtestfor2354889' => ['missing_context_ids' => ['baloney.spam' => ['node_type']], 'status' => TRUE]], \Drupal::keyValue('update_backup')->get('block_update_8001'));
+
+    $disabled_block_visibility = $disabled_block->get('visibility');
+    $this->assertTrue(!isset($disabled_block_visibility['node_type']), 'The problematic visibility condition has been removed.');
+
+    $admin_user = $this->drupalCreateUser(['administer blocks']);
+    $this->drupalLogin($admin_user);
+
+    $this->drupalGet('admin/structure/block/manage/thirdtestfor2354889');
+    $this->assertResponse('200');
+  }
+
+}
diff --git a/core/modules/block/tests/modules/block_test/src/Plugin/Condition/BaloneySpam.php b/core/modules/block/tests/modules/block_test/src/Plugin/Condition/BaloneySpam.php
new file mode 100644
index 0000000..55e12ab
--- /dev/null
+++ b/core/modules/block/tests/modules/block_test/src/Plugin/Condition/BaloneySpam.php
@@ -0,0 +1,37 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\block_test\Plugin\Condition\BaloneySpam.
+ */
+
+namespace Drupal\block_test\Plugin\Condition;
+
+use Drupal\Core\Condition\ConditionPluginBase;
+
+/**
+ * Provides a 'baloney.spam' condition.
+ *
+ * @Condition(
+ *   id = "baloney.spam",
+ *   label = @Translation("Baloney spam"),
+ * )
+ *
+ */
+class BaloneySpam extends ConditionPluginBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function evaluate() {
+    return TRUE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function summary() {
+    return 'Summary';
+  }
+
+}
diff --git a/core/modules/system/src/Tests/Update/UpdatePathTestBase.php b/core/modules/system/src/Tests/Update/UpdatePathTestBase.php
index fb365f0..da0b3be 100644
--- a/core/modules/system/src/Tests/Update/UpdatePathTestBase.php
+++ b/core/modules/system/src/Tests/Update/UpdatePathTestBase.php
@@ -185,7 +185,13 @@ protected function runUpdates() {
       $this->fail('Missing zlib requirement for upgrade tests.');
       return FALSE;
     }
-    $this->drupalLogin($this->rootUser);
+    // The site might be broken at the time so logging in using the UI might
+    // not work, so we use the API itself.
+    drupal_rewrite_settings(['settings' => ['update_free_access' => (object) [
+      'value' => TRUE,
+      'required' => TRUE,
+    ]]]);
+
     $this->drupalGet($this->updateUrl);
     $this->clickLink(t('Continue'));
 
diff --git a/core/modules/system/system.routing.yml b/core/modules/system/system.routing.yml
index 9d806bb..a656ab3 100644
--- a/core/modules/system/system.routing.yml
+++ b/core/modules/system/system.routing.yml
@@ -454,6 +454,8 @@ system.db_update:
     _title: 'Drupal database update'
     _controller: '\Drupal\system\Controller\DbUpdateController::handle'
     op: 'info'
+  options:
+    _maintenance_access: TRUE
   requirements:
     _access_system_update: 'TRUE'
 
diff --git a/core/modules/system/tests/fixtures/update/block.block.secondtestfor2354889.yml b/core/modules/system/tests/fixtures/update/block.block.secondtestfor2354889.yml
new file mode 100644
index 0000000..1a8a904
--- /dev/null
+++ b/core/modules/system/tests/fixtures/update/block.block.secondtestfor2354889.yml
@@ -0,0 +1,23 @@
+uuid: C499B41D-035E-432E-9462-36410C43C49F
+langcode: en
+status: true
+dependencies:
+  module:
+    - search
+  theme:
+    - bartik
+id: secondtestfor2354889
+theme: bartik
+region: sidebar_first
+weight: -6
+provider: null
+plugin: search_form_block
+settings:
+  id: search_form_block
+  label: Search
+  provider: search
+  label_display: visible
+  cache:
+    max_age: -1
+  status: true
+visibility: {  }
diff --git a/core/modules/system/tests/fixtures/update/block.block.testfor2354889.yml b/core/modules/system/tests/fixtures/update/block.block.testfor2354889.yml
new file mode 100644
index 0000000..d2ac964
--- /dev/null
+++ b/core/modules/system/tests/fixtures/update/block.block.testfor2354889.yml
@@ -0,0 +1,51 @@
+uuid: 9d204071-a923-4707-8200-c298a540fb0c
+langcode: en
+status: true
+dependencies:
+  content:
+    - 'block_content:basic:c1895145-893e-460b-a24e-78cd2cefbb1f'
+  module:
+    - block_content
+    - node
+    - user
+  theme:
+    - bartik
+id: testfor2354889
+theme: bartik
+region: content
+weight: -6
+provider: null
+plugin: 'block_content:c1895145-893e-460b-a24e-78cd2cefbb1f'
+settings:
+  id: 'block_content:c1895145-893e-460b-a24e-78cd2cefbb1f'
+  label: 'Test for 2354889'
+  provider: block_content
+  label_display: visible
+  cache:
+    max_age: -1
+  status: true
+  info: ''
+  view_mode: full
+visibility:
+  node_type:
+    id: node_type
+    bundles:
+      page: page
+    negate: false
+    context_mapping:
+      node: node.node
+  user_role:
+    id: user_role
+    roles:
+      authenticated: authenticated
+    negate: false
+    context_mapping:
+      user: user.current_user
+  language:
+    id: language
+    langcodes:
+      en: en
+      de: de
+    negate: false
+    context_mapping:
+      language: language.language_interface
diff --git a/core/modules/system/tests/fixtures/update/block.block.thirdtestfor2354889.yml b/core/modules/system/tests/fixtures/update/block.block.thirdtestfor2354889.yml
new file mode 100644
index 0000000..472e131
--- /dev/null
+++ b/core/modules/system/tests/fixtures/update/block.block.thirdtestfor2354889.yml
@@ -0,0 +1,30 @@
+uuid: 4558907D-2918-48FE-B56F-8A007B5FBDD5
+langcode: en
+status: true
+dependencies:
+  module:
+    - user
+  theme:
+    - bartik
+id: thirdtestfor2354889
+theme: bartik
+region: sidebar_first
+weight: -6
+provider: null
+plugin: user_login_block
+settings:
+  id: user_login_block
+  label: 'User login'
+  provider: user
+  label_display: visible
+  cache:
+    max_age: -1
+  status: true
+visibility:
+  node_type:
+    id: node_type
+    bundles:
+      page: page
+    negate: false
+    context_mapping:
+      baloney: baloney.spam
diff --git a/core/modules/system/tests/fixtures/update/drupal-8.block-context-manager-2354889.php b/core/modules/system/tests/fixtures/update/drupal-8.block-context-manager-2354889.php
new file mode 100644
index 0000000..23b67e5
--- /dev/null
+++ b/core/modules/system/tests/fixtures/update/drupal-8.block-context-manager-2354889.php
@@ -0,0 +1,53 @@
+<?php
+
+/**
+ * @file
+ * Contains database additions to drupal-8.bare.standard.php.gz for testing the
+ * upgrade path of https://www.drupal.org/node/2354889.
+ */
+
+use Drupal\Core\Database\Database;
+
+$connection = Database::getConnection();
+
+// A custom block with visibility settings.
+$block_configs[] = \Drupal\Component\Serialization\Yaml::decode(file_get_contents(__DIR__ . '/block.block.testfor2354889.yml'));
+
+// A custom block without any visibility settings.
+$block_configs[] = \Drupal\Component\Serialization\Yaml::decode(file_get_contents(__DIR__ . '/block.block.secondtestfor2354889.yml'));
+
+// A custom block with visibility settings that contain a non-existing context
+// mapping.
+$block_configs[] = \Drupal\Component\Serialization\Yaml::decode(file_get_contents(__DIR__ . '/block.block.thirdtestfor2354889.yml'));
+
+foreach ($block_configs as $block_config) {
+  $connection->insert('config')
+    ->fields(array(
+      'collection',
+      'name',
+      'data',
+    ))
+    ->values(array(
+      'collection' => '',
+      'name' => 'block.block.' . $block_config['id'],
+      'data' => serialize($block_config),
+    ))
+    ->execute();
+}
+
+// Update the config entity query "index".
+$existing_blocks = $connection->select('key_value')
+  ->fields('key_value', ['value'])
+  ->condition('collection', 'config.entity.key_store.block')
+  ->condition('name', 'theme:bartik')
+  ->execute()
+  ->fetchField();
+$existing_blocks = unserialize($existing_blocks);
+
+$connection->update('key_value')
+  ->fields([
+    'value' => serialize(array_merge($existing_blocks, ['block.block.testfor2354889', 'block.block.secondtestfor2354889', 'block.block.thirdtestfor2354889']))
+  ])
+  ->condition('collection', 'config.entity.key_store.block')
+  ->condition('name', 'theme:bartik')
+  ->execute();