diff --git a/core/modules/block/lib/Drupal/block/BlockStorageController.php b/core/modules/block/lib/Drupal/block/BlockStorageController.php
index 9cdf1a7..3997704 100644
--- a/core/modules/block/lib/Drupal/block/BlockStorageController.php
+++ b/core/modules/block/lib/Drupal/block/BlockStorageController.php
@@ -16,6 +16,17 @@
 class BlockStorageController extends ConfigStorageController {
 
   /**
+   * Overrides \Drupal\Core\Config\Entity\ConfigStorageController::load().
+   */
+  public function load(array $ids = NULL) {
+    $entities = parent::load($ids);
+    // Only blocks with a valid plugin should be loaded.
+    return array_filter($entities, function ($entity) {
+      return $entity->getPlugin();
+    });
+  }
+
+  /**
    * Overrides \Drupal\Core\Config\Entity\ConfigStorageController::loadByProperties().
    */
   public function loadByProperties(array $values = array()) {
diff --git a/core/modules/block/lib/Drupal/block/Plugin/Core/Entity/Block.php b/core/modules/block/lib/Drupal/block/Plugin/Core/Entity/Block.php
index 572d5e1..775ecfa 100644
--- a/core/modules/block/lib/Drupal/block/Plugin/Core/Entity/Block.php
+++ b/core/modules/block/lib/Drupal/block/Plugin/Core/Entity/Block.php
@@ -10,6 +10,7 @@
 use Drupal\Core\Config\Entity\ConfigEntityBase;
 use Drupal\Core\Annotation\Plugin;
 use Drupal\Core\Annotation\Translation;
+use Drupal\Component\Plugin\Exception\PluginException;
 
 /**
  * Defines a Block configuration entity class.
@@ -132,13 +133,27 @@ class Block extends ConfigEntityBase {
   public function __construct(array $values, $entity_type) {
     parent::__construct($values, $entity_type);
 
-    $this->instance = drupal_container()->get('plugin.manager.block')->createInstance($this->plugin, $this->configuration);
-    $this->configuration += $this->instance->getConfig();
+    // @todo Consider moving to Block::getPlugin().
+    try {
+      $this->instance = drupal_container()->get('plugin.manager.block')->createInstance($this->plugin, $this->configuration);
+      $this->configuration += $this->instance->getConfig();
+    }
+    catch (PluginException $e) {
+      // Ignore blocks belonging to disabled modules, but re-throw valid
+      // exceptions when the module is enabled and the plugin is misconfigured.
+      if (module_exists($this->module)) {
+        throw $e;
+      }
+    }
 
+    // @todo Consider moving to \Drupal\block\BlockStorageController::create().
+    if (!$this->module) {
+      $definition = $this->instance->getDefinition();
+      $this->module = $definition['module'];
+    }
     if (isset($this->configuration['cache'])) {
       $this->cache = $this->configuration['cache'];
     }
-
     if (!isset($this->theme) && $id = $this->id()) {
       list($this->theme) = explode('.', $id);
     }
diff --git a/core/modules/block/lib/Drupal/block/Tests/BlockLibrarySearchTest.php b/core/modules/block/lib/Drupal/block/Tests/BlockLibrarySearchTest.php
index dc93755..22f47e8 100644
--- a/core/modules/block/lib/Drupal/block/Tests/BlockLibrarySearchTest.php
+++ b/core/modules/block/lib/Drupal/block/Tests/BlockLibrarySearchTest.php
@@ -54,6 +54,7 @@ function testBlockLibrarySearch() {
 
     // Check that the block search form redirects to the correct block form.
     $this->drupalPost('admin/structure/block/list/block_plugin_ui:stark/add', array('block' => 'system_main_block'), t('Next'));
-    $this->assertUrl('admin/structure/block/manage/system_main_block/stark');
+    $this->assertUrl('admin/structure/block/add/system_main_block/stark');
   }
+
 }
diff --git a/core/modules/block/lib/Drupal/block/Tests/BlockTemplateSuggestionsUnitTest.php b/core/modules/block/lib/Drupal/block/Tests/BlockTemplateSuggestionsUnitTest.php
index 089b9a7..c469eb6 100644
--- a/core/modules/block/lib/Drupal/block/Tests/BlockTemplateSuggestionsUnitTest.php
+++ b/core/modules/block/lib/Drupal/block/Tests/BlockTemplateSuggestionsUnitTest.php
@@ -40,15 +40,21 @@ function testBlockThemeHookSuggestions() {
     $block = entity_create('block', array(
       'plugin' => 'system_menu_block:menu-admin',
       'region' => 'footer',
+      'id' => variable_get('theme_default', 'stark') . '.machinename',
     ));
 
     $variables = array();
     $variables['elements']['#block'] = $block;
+    $variables['elements']['#block_config'] = $block->getPlugin()->getConfig() + array(
+      'id' => $block->get('plugin'),
+      'region' => $block->get('region'),
+      'module' => $block->get('module'),
+    );
     $variables['elements']['#children'] = '';
     // Test adding a class to the block content.
     $variables['content_attributes']['class'][] = 'test-class';
     template_preprocess_block($variables);
-    $this->assertEqual($variables['theme_hook_suggestions'], array('block__footer', 'block__system', 'block__system_menu_block', 'block__system_menu_block__menu_admin'));
+    $this->assertEqual($variables['theme_hook_suggestions'], array('block__footer', 'block__system', 'block__system_menu_block', 'block__system_menu_block__menu_admin', 'block__machinename'));
     $this->assertEqual($variables['content_attributes']['class'], array('test-class', 'content'), 'Default .content class added to block content_attributes_array');
   }
 
diff --git a/core/modules/block/lib/Drupal/block/Tests/BlockTest.php b/core/modules/block/lib/Drupal/block/Tests/BlockTest.php
index c5cc7f5..274ddb2 100644
--- a/core/modules/block/lib/Drupal/block/Tests/BlockTest.php
+++ b/core/modules/block/lib/Drupal/block/Tests/BlockTest.php
@@ -389,7 +389,7 @@ function testBlockModuleDisable() {
     }
     $this->drupalGet('');
     foreach ($regions as $region) {
-      $this->assertText($blocks[$region]['subject']);
+      $this->assertText($blocks[$region]->label());
     }
 
     // Disable the block test module and refresh the definitions cache.
@@ -405,7 +405,7 @@ function testBlockModuleDisable() {
 
     // Ensure that the disabled module's block instance is not listed.
     foreach ($regions as $region) {
-      $this->assertNoText($blocks[$region]['subject']);
+      $this->assertNoText($blocks[$region]->label());
     }
 
     // Ensure that the disabled module's block plugin is no longer available.
@@ -416,7 +416,7 @@ function testBlockModuleDisable() {
     $this->drupalGet('');
     $this->assertResponse(200);
     foreach ($regions as $region) {
-      $this->assertNoText($blocks[$region]['subject']);
+      $this->assertNoText($blocks[$region]->label());
     }
 
     // Confirm that a different block instance can still be enabled by
@@ -424,16 +424,16 @@ function testBlockModuleDisable() {
     // Emulate a POST submission rather than using drupalPlaceBlock() to ensure
     // that the form still functions as expected.
     $edit = array(
-      'title' => $this->randomName(8),
+      'label' => $this->randomName(8),
       'machine_name' => $this->randomName(8),
       'region' => 'sidebar_first',
     );
-    $this->drupalPost('admin/structure/block/manage/system_powered_by_block/stark', $edit, t('Save block'));
+    $this->drupalPost('admin/structure/block/add/system_powered_by_block/stark', $edit, t('Save block'));
     $this->assertText(t('The block configuration has been saved.'));
-    $this->assertText($edit['title']);
+    $this->assertText($edit['label']);
 
     // Update the weight of a block.
-    $edit = array('blocks[0][weight]' => -1);
+    $edit = array('blocks[stark.' . $edit['machine_name'] . '][weight]' => -1);
     $this->drupalPost('admin/structure/block', $edit, t('Save blocks'));
     $this->assertText(t('The block settings have been updated.'));
 
@@ -445,7 +445,7 @@ function testBlockModuleDisable() {
     // Reload the admin page and confirm the block can again be configured.
     $this->drupalGet('admin/structure/block');
     foreach ($regions as $region) {
-      $this->assertLinkByHref(url('admin/structure/block/manage/' . $blocks[$region]['config_id'] . '/stark/config'));
+      $this->assertLinkByHref(url('admin/structure/block/manage/' . $blocks[$region]->id()));
     }
 
     // Confirm that the blocks are again displayed on the front page in the
@@ -453,14 +453,14 @@ function testBlockModuleDisable() {
     $this->drupalGet('');
     foreach ($regions as $region) {
       // @todo Use a proper method for this.
-      $name_pieces = explode('.', $blocks[$region]['config_id']);
+      $name_pieces = explode('.', $blocks[$region]->id());
       $machine_name = array_pop($name_pieces);
       $xpath = $this->buildXPathQuery('//div[@class=:region-class]//div[@id=:block-id]/*', array(
         ':region-class' => 'region region-' . drupal_html_class($region),
         ':block-id' => 'block-' . strtr(strtolower($machine_name), '-', '_'),
     ));
       $this->assertFieldByXPath($xpath, NULL, format_string('Block %name found in the %region region.', array(
-        '%name' => $blocks[$region]['subject'],
+        '%name' => $blocks[$region]->label(),
         '%region' => $region,
       )));
     }