diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Plugin/Derivative/CategoryBlock.php b/core/modules/aggregator/lib/Drupal/aggregator/Plugin/Derivative/CategoryBlock.php
index 1bd3af8..0ba054c 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Plugin/Derivative/CategoryBlock.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Plugin/Derivative/CategoryBlock.php
@@ -27,7 +27,7 @@ public function getDerivativeDefinition($derivative_id, array $base_plugin_defin
   public function getDerivativeDefinitions(array $base_plugin_definition) {
     $result = db_query('SELECT cid, title FROM {aggregator_category} ORDER BY title');
     foreach ($result as $category) {
-      $this->derivatives[$category->cid] = $this->config;
+      $this->derivatives[$category->cid] = $base_plugin_definition;
       $this->derivatives[$category->cid]['delta'] = $category->cid;
       $this->derivatives[$category->cid]['subject'] = t('@title category latest items', array('@title' => $category->title));
     }
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Plugin/Derivative/FeedBlock.php b/core/modules/aggregator/lib/Drupal/aggregator/Plugin/Derivative/FeedBlock.php
index 3daf44e..a444be2 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Plugin/Derivative/FeedBlock.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Plugin/Derivative/FeedBlock.php
@@ -27,7 +27,7 @@ public function getDerivativeDefinition($derivative_id, array $base_plugin_defin
   public function getDerivativeDefinitions(array $base_plugin_definition) {
     $result = db_query('SELECT fid, title FROM {aggregator_feed} WHERE block <> 0 ORDER BY fid');
     foreach ($result as $feed) {
-      $this->derivatives[$feed->fid] = $this->config;
+      $this->derivatives[$feed->fid] = $base_plugin_definition;
       $this->derivatives[$feed->fid]['delta'] = $feed->fid;
       $this->derivatives[$feed->fid]['subject'] = t('@title feed latest items', array('@title' => $feed->title));
     }
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Plugin/block/block/CategoryBlock.php b/core/modules/aggregator/lib/Drupal/aggregator/Plugin/block/block/CategoryBlock.php
index e65ad2a..c7cd27e 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Plugin/block/block/CategoryBlock.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Plugin/block/block/CategoryBlock.php
@@ -39,7 +39,7 @@ public function configure($form, &$form_state) {
     $form['block_count'] = array(
       '#type' => 'select',
       '#title' => t('Number of news items in block'),
-      '#default_value' => $this->config['settings']['block_count'],
+      '#default_value' => $this->configuration['block_count'],
       '#options' => drupal_map_assoc(range(2, 20)),
     );
     return $form;
@@ -49,7 +49,7 @@ public function configure($form, &$form_state) {
    * Implements BlockInterface::configureSubmit().
    */
   public function configureSubmit($form, &$form_state) {
-    $this->config['settings']['block_count'] = $form_state['values']['block_count'];
+    $this->configuration['block_count'] = $form_state['values']['block_count'];
   }
 
   /**
@@ -58,7 +58,7 @@ public function configureSubmit($form, &$form_state) {
   public function build() {
     $id = $this->getPluginId();
     if ($category = db_query('SELECT cid, title, block FROM {aggregator_category} WHERE cid = :cid', array(':cid' => $id))->fetchObject()) {
-      $result = db_query_range('SELECT i.* FROM {aggregator_category_item} ci LEFT JOIN {aggregator_item} i ON ci.iid = i.iid WHERE ci.cid = :cid ORDER BY i.timestamp DESC, i.iid DESC', 0, $this->config['settings']['block_count'], array(':cid' => $category->cid));
+      $result = db_query_range('SELECT i.* FROM {aggregator_category_item} ci LEFT JOIN {aggregator_item} i ON ci.iid = i.iid WHERE ci.cid = :cid ORDER BY i.timestamp DESC, i.iid DESC', 0, $this->configuration['block_count'], array(':cid' => $category->cid));
       $read_more = theme('more_link', array('url' => 'aggregator/categories/' . $category->cid, 'title' => t("View this category's recent news.")));
 
       $items = array();
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Plugin/block/block/FeedBlock.php b/core/modules/aggregator/lib/Drupal/aggregator/Plugin/block/block/FeedBlock.php
index db418ec..a2a0742 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Plugin/block/block/FeedBlock.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Plugin/block/block/FeedBlock.php
@@ -39,7 +39,7 @@ public function configure($form, &$form_state) {
     $form['block_count'] = array(
       '#type' => 'select',
       '#title' => t('Number of news items in block'),
-      '#default_value' => $this->config['block_count'],
+      '#default_value' => $this->configuration['block_count'],
       '#options' => drupal_map_assoc(range(2, 20)),
     );
     return $form;
@@ -49,23 +49,23 @@ public function configure($form, &$form_state) {
    * Implements BlockInterface::configureSubmit().
    */
   public function configureSubmit($form, &$form_state) {
-    $this->config['block_count'] = $form_state['values']['block_count'];
+    $this->configuration['block_count'] = $form_state['values']['block_count'];
   }
 
   /**
    * Implements BlockInterface::build().
    */
   public function build() {
-    $id = $this->getPluginId();
+    // Plugin ids look something like this: aggregator_feed_block:1.
+    $id = substr($this->getPluginId(), 22);
     if ($feed = db_query('SELECT fid, title, block FROM {aggregator_feed} WHERE block <> 0 AND fid = :fid', array(':fid' => $id))->fetchObject()) {
-      $result = db_query_range("SELECT * FROM {aggregator_item} WHERE fid = :fid ORDER BY timestamp DESC, iid DESC", 0, $this->config['block_count'], array(':fid' => $id));
+      $result = db_query_range("SELECT * FROM {aggregator_item} WHERE fid = :fid ORDER BY timestamp DESC, iid DESC", 0, $this->configuration['block_count'], array(':fid' => $id));
       $read_more = theme('more_link', array('url' => 'aggregator/sources/' . $feed->fid, 'title' => t("View this feed's recent news.")));
 
       $items = array();
       foreach ($result as $item) {
         $items[] = theme('aggregator_block_item', array('item' => $item));
       }
-
       // Only display the block if there are items to show.
       if (count($items) > 0) {
         return array(
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorRenderingTest.php b/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorRenderingTest.php
index 7f09317..60e999e 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorRenderingTest.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorRenderingTest.php
@@ -27,7 +27,6 @@ public function testBlockLinks() {
     $feed = $this->createFeed();
     $this->updateFeedItems($feed, $this->getDefaultFeedItemCount());
 
-    // Place block on page (@see block.test:moveBlockToRegion())
     // Need admin user to be able to access block admin.
     $this->admin_user = $this->drupalCreateUser(array(
       'administer blocks',
@@ -37,21 +36,17 @@ public function testBlockLinks() {
     ));
     $this->drupalLogin($this->admin_user);
 
-    // Prepare to use the block admin form.
+    $current_theme = variable_get('default_theme', 'stark');
+    $machine_name = 'test_aggregator_feed_block';
     $block = array(
-      'module' => 'aggregator',
-      'delta' => 'feed-' . $feed->fid,
-      'title' => $feed->title,
+      'machine_name' => $machine_name,
+      'region' => 'footer',
+      'title' => 'feed-' . $feed->title,
+      'block_count' => 2,
     );
-    $region = 'footer';
-    $edit = array();
-    $edit['blocks[' . $block['module'] . '_' . $block['delta'] . '][region]'] = $region;
-    // Check the feed block is available in the block list form.
-    $this->drupalGet('admin/structure/block');
-    $this->assertFieldByName('blocks[' . $block['module'] . '_' . $block['delta'] . '][region]', '', 'Aggregator feed block is available for positioning.');
-    // Position it.
-    $this->drupalPost('admin/structure/block', $edit, t('Save blocks'));
-    $this->assertText(t('The block settings have been updated.'), format_string('Block successfully moved to %region_name region.', array( '%region_name' => $region)));
+    $this->drupalPost("admin/structure/block/manage/aggregator_feed_block:{$feed->fid}/$current_theme", $block, t('Save block'));
+    $this->assertText(t('The block configuration has been saved.'), 'Block was saved.');
+
     // Confirm that the block is now being displayed on pages.
     $this->drupalGet('node');
     $this->assertText(t($block['title']), 'Feed block is displayed on the page.');
diff --git a/core/modules/block/block.install b/core/modules/block/block.install
index da301c1..520689b 100644
--- a/core/modules/block/block.install
+++ b/core/modules/block/block.install
@@ -75,7 +75,6 @@ function block_schema() {
       'pages' => array(
         'type' => 'text',
         'not null' => TRUE,
-        'default' => '',
         'description' => 'Contents of the "Pages" block; contains either a list of paths on which to include/exclude the block or PHP code, depending on "visibility" setting.',
       ),
       'title' => array(
diff --git a/core/modules/comment/lib/Drupal/comment/Tests/CommentBlockTest.php b/core/modules/comment/lib/Drupal/comment/Tests/CommentBlockTest.php
index 0ec3af2..b8c07e6 100644
--- a/core/modules/comment/lib/Drupal/comment/Tests/CommentBlockTest.php
+++ b/core/modules/comment/lib/Drupal/comment/Tests/CommentBlockTest.php
@@ -46,21 +46,16 @@ public static function getInfo() {
    */
   function testRecentCommentBlock() {
     $this->drupalLogin($this->admin_user);
-
-    // Set the block to a region to confirm block is available.
+    $current_theme = variable_get('default_theme', 'stark');
+    $machine_name = 'test_recent_comments';
     $edit = array(
-      'blocks[comment_recent][region]' => 'sidebar_first',
-    );
-    $this->drupalPost('admin/structure/block', $edit, t('Save blocks'));
-    $this->assertText(t('The block settings have been updated.'), 'Block saved to first sidebar region.');
-
-    // Set block title and variables.
-    $block = array(
+      'machine_name' => $machine_name,
+      'region' => 'sidebar_first',
       'title' => $this->randomName(),
-      'comment_block_count' => 2,
+      'block_count' => 2,
     );
-    $this->drupalPost('admin/structure/block/manage/comment/recent/configure', $block, t('Save block'));
-    $this->assertText(t('The block configuration has been saved.'), 'Block saved.');
+    $this->drupalPost('admin/structure/block/manage/recent_comments/' . $current_theme, $edit, t('Save block'));
+    $this->assertText(t('The block configuration has been saved.'), 'Block was saved.');
 
     // Add some test comments, one without a subject.
     $comment1 = $this->postComment($this->node, $this->randomName(), $this->randomName());
@@ -75,14 +70,14 @@ function testRecentCommentBlock() {
     // posting a node from a node form.
     cache_invalidate(array('content' => TRUE));
     $this->drupalGet('');
-    $this->assertNoText($block['title'], 'Block was not found.');
+    $this->assertNoText($edit['title'], 'Block was not found.');
     user_role_grant_permissions(DRUPAL_ANONYMOUS_RID, array('access comments'));
 
     // Test that a user with the 'access comments' permission can see the
     // block.
     $this->drupalLogin($this->web_user);
     $this->drupalGet('');
-    $this->assertText($block['title'], 'Block was found.');
+    $this->assertText($edit['title'], 'Block was found.');
 
     // Test the only the 2 latest comments are shown and in the proper order.
     $this->assertNoText($comment1->subject, 'Comment not found in block.');
@@ -94,9 +89,10 @@ function testRecentCommentBlock() {
     $this->drupalLogout();
     $this->drupalLogin($this->admin_user);
     $block = array(
-      'comment_block_count' => 10,
+      'block_count' => 10,
     );
-    $this->drupalPost('admin/structure/block/manage/comment/recent/configure', $block, t('Save block'));
+
+    $this->drupalPost("admin/structure/block/manage/plugin.core.block.$current_theme.$machine_name/$current_theme/configure", $block, t('Save block'));
     $this->assertText(t('The block configuration has been saved.'), 'Block saved.');
 
     // Post an additional comment.