diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index 2fa1796..1eb63b6 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -2493,9 +2493,6 @@ function drupal_container(Container $new_container = NULL, $rebuild = FALSE) {
 
     // Register the EntityManager.
     $container->register('plugin.manager.entity', 'Drupal\Core\Entity\EntityManager');
-
-    // Register the Plugin UI.
-    $container->register('plugin.manager.system.plugin_ui', 'Drupal\system\Plugin\Type\PluginUIManager');
   }
   return $container;
 }
diff --git a/core/lib/Drupal/Core/DrupalKernel.php b/core/lib/Drupal/Core/DrupalKernel.php
index b429d6c..072e109 100644
--- a/core/lib/Drupal/Core/DrupalKernel.php
+++ b/core/lib/Drupal/Core/DrupalKernel.php
@@ -204,12 +204,6 @@ public function updateModules(array $module_list, array $module_paths = array())
     // list will take effect when boot() is called. If we have already booted,
     // then reboot in order to refresh the bundle list and container.
     if ($this->booted) {
-      // @todo Determine if there is another way to prevent old containers from
-      //   being used.
-      // Explicitly prevent old compiled containers from being used.
-      if ($this->compilationIndexCache) {
-        $this->compilationIndexCache->flush();
-      }
       drupal_container(NULL, TRUE);
       $this->booted = FALSE;
       $this->boot();
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Plugin/block/block/FeedBlock.php b/core/modules/aggregator/lib/Drupal/aggregator/Plugin/block/block/FeedBlock.php
index 963e3b1..909f676 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Plugin/block/block/FeedBlock.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Plugin/block/block/FeedBlock.php
@@ -63,8 +63,8 @@ public function configureSubmit($form, &$form_state) {
    * Overrides \Drupal\block\BlockBase::build().
    */
   public function build() {
-    // Plugin ids look something like this: aggregator_feed_block:1.
-    $id = substr($this->getPluginId(), 22);
+    // Plugin IDs look something like this: aggregator_feed_block:1.
+    list(, $id) = explode(':', $this->getPluginId());
     if ($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->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.")));
diff --git a/core/modules/block/block.module b/core/modules/block/block.module
index a2bfdef..5ce5a21 100644
--- a/core/modules/block/block.module
+++ b/core/modules/block/block.module
@@ -141,7 +141,7 @@ function block_menu() {
   // Block administration is actually tied to theme and plugin definition so
   // that the plugin can appropriately attach to this url structure.
   $themes = list_themes();
-  foreach (system_plugin_manager('plugin_ui')->getDefinitions() as $plugin_id => $plugin) {
+  foreach (drupal_container()->get('plugin.manager.system.plugin_ui')->getDefinitions() as $plugin_id => $plugin) {
     list($plugin_base, $key) = explode(':', $plugin_id);
     if ($plugin_base == 'block_plugin_ui') {
       $theme = $themes[$key];
@@ -461,13 +461,6 @@ function block_list($region) {
 }
 
 /**
- * Returns the block plugin manager from the dependency injection container.
- */
-function block_manager() {
-  return drupal_container()->get('plugin.manager.block');
-}
-
-/**
  * Loads a block object from the database.
  *
  * @param string $plugin_id
@@ -480,11 +473,12 @@ function block_manager() {
  *   A block object.
  */
 function block_load($plugin_id, array $conf = array()) {
+  $manager = drupal_container()->get('plugin.manager.block');
   try {
-    $block = block_manager()->getInstance(array('config' => $plugin_id));
+    $block = $manager->getInstance(array('config' => $plugin_id));
   }
   catch (Drupal\Component\Plugin\Exception\PluginException $e) {
-    $block = block_manager()->createInstance($plugin_id, $conf);
+    $block = $manager->createInstance($plugin_id, $conf);
   }
   return $block;
 }
@@ -499,7 +493,7 @@ function _block_load_blocks() {
   global $theme;
   $blocks = array();
   $instances = config_get_storage_names_with_prefix('plugin.core.block.' . $theme);
-  $manager = block_manager();
+  $manager = drupal_container()->get('plugin.manager.block');
   foreach ($instances as $plugin_id) {
     $block = $manager->getInstance(array('config' => $plugin_id));
     $config = $block->getConfig();
@@ -540,6 +534,8 @@ function _block_get_renderable_block($element) {
 /**
  * Wrapper for $block->build to allow altering of blocks.
  *
+ * @todo Move the alter invocation into a plugin method.
+ *
  * @param \Drupal\block\BlockInterface $block
  *   The block instance.
  *
diff --git a/core/modules/block/custom_block/custom_block.admin.inc b/core/modules/block/custom_block/custom_block.admin.inc
index 1d9c7d0..a45a0bf 100644
--- a/core/modules/block/custom_block/custom_block.admin.inc
+++ b/core/modules/block/custom_block/custom_block.admin.inc
@@ -21,9 +21,7 @@ function custom_block_admin_custom_block($form, &$form_state) {
   );
   $header = array(t('Administrative Title'), t('Operations'));
   $options = array();
-  $results = db_select('block_custom', 'cb')
-    ->fields('cb')
-    ->execute();
+  $results = db_query('SELECT * FROM {block_custom}');
   foreach ($results as $result) {
     $options[$result->bid] = array(
       array(
diff --git a/core/modules/block/custom_block/custom_block.module b/core/modules/block/custom_block/custom_block.module
index 83e15d8..c70b285 100644
--- a/core/modules/block/custom_block/custom_block.module
+++ b/core/modules/block/custom_block/custom_block.module
@@ -10,7 +10,7 @@
  */
 function custom_block_menu() {
   $items = array();
-  foreach (system_plugin_manager('plugin_ui')->getDefinitions() as $plugin_id => $plugin) {
+  foreach (drupal_container()->get('plugin.manager.system.plugin_ui')->getDefinitions() as $plugin_id => $plugin) {
     // We only need this menu item for the block_plugin_ui derivatives.
     if (strpos($plugin_id, 'block_plugin_ui') === 0) {
       list(, $theme) = explode(':', $plugin_id);
diff --git a/core/modules/block/custom_block/lib/Drupal/custom_block/Plugin/Derivative/CustomBlock.php b/core/modules/block/custom_block/lib/Drupal/custom_block/Plugin/Derivative/CustomBlock.php
index 71531e2..23cc00a 100644
--- a/core/modules/block/custom_block/lib/Drupal/custom_block/Plugin/Derivative/CustomBlock.php
+++ b/core/modules/block/custom_block/lib/Drupal/custom_block/Plugin/Derivative/CustomBlock.php
@@ -34,20 +34,16 @@ public function getDerivativeDefinition($derivative_id, array $base_plugin_defin
    * Implements \Drupal\Component\Plugin\Derivative\DerivativeInterface::getDerivativeDefinitions().
    */
   public function getDerivativeDefinitions(array $base_plugin_definition) {
-    $results = db_select('block_custom', 'b')
-      ->fields('b')
-      ->execute();
-    if ($results) {
-      foreach ($results as $result) {
-        $this->derivatives[$result->bid] = $base_plugin_definition;
-        $this->derivatives[$result->bid]['settings'] = array(
-          'info' => $result->info,
-          'body' => $result->body,
-          'format' => $result->format,
-        ) + $base_plugin_definition['settings'];
-        $this->derivatives[$result->bid]['subject'] = $result->info;
-        unset($this->derivatives[$result->bid]['custom']);
-      }
+    $results = db_query('SELECT * FROM {block_custom}');
+    foreach ($results as $result) {
+      $this->derivatives[$result->bid] = $base_plugin_definition;
+      $this->derivatives[$result->bid]['settings'] = array(
+        'info' => $result->info,
+        'body' => $result->body,
+        'format' => $result->format,
+      ) + $base_plugin_definition['settings'];
+      $this->derivatives[$result->bid]['subject'] = $result->info;
+      unset($this->derivatives[$result->bid]['custom']);
     }
     $this->derivatives['custom_block'] = $base_plugin_definition;
     return $this->derivatives;
diff --git a/core/modules/block/lib/Drupal/block/Tests/BlockTemplateSuggestionsUnitTest.php b/core/modules/block/lib/Drupal/block/Tests/BlockTemplateSuggestionsUnitTest.php
index 4078132..c72236d 100644
--- a/core/modules/block/lib/Drupal/block/Tests/BlockTemplateSuggestionsUnitTest.php
+++ b/core/modules/block/lib/Drupal/block/Tests/BlockTemplateSuggestionsUnitTest.php
@@ -42,7 +42,7 @@ function testBlockThemeHookSuggestions() {
     );
 
     // $block3 = block_load('system_powered_by_block', $data3);
-    $block = block_manager()->createInstance('system_menu_block:menu-admin', $data);
+    $block = drupal_container()->get('plugin.manager.block')->createInstance('system_menu_block:menu-admin', $data);
     $variables = array();
     $variables['elements']['#block'] = $block;
     $variables['elements']['#children'] = '';
diff --git a/core/modules/block/lib/Drupal/block/Tests/BlockTest.php b/core/modules/block/lib/Drupal/block/Tests/BlockTest.php
index 1dec612..8686a25 100644
--- a/core/modules/block/lib/Drupal/block/Tests/BlockTest.php
+++ b/core/modules/block/lib/Drupal/block/Tests/BlockTest.php
@@ -258,7 +258,7 @@ function testBlockRehash() {
     $this->assertTrue(module_exists('block_test'), 'Test block module enabled.');
 
     // Add a test block.
-    $plugin = block_manager()->getDefinition('test_cache');
+    $plugin = drupal_container()->get('plugin.manager.block')->getDefinition('test_cache');
 
     $block = array();
     $block['id'] = 'test_cache';
diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index be4f7fa..461afb8 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -1079,7 +1079,7 @@ function system_menu() {
     );
   }
 
-  foreach (system_plugin_manager('plugin_ui')->getDefinitions() as $plugin_id => $plugin) {
+  foreach (drupal_container()->get('plugin.manager.system.plugin_ui')->getDefinitions() as $plugin_id => $plugin) {
     if ($plugin['menu'] === TRUE) {
       $items[$plugin['path'] . '/' . $plugin_id . '/' . $plugin['suffix']] = array(
         'title' => $plugin['title'],
@@ -1129,7 +1129,7 @@ function system_menu() {
  * A simple wrapper function for proxying to the plugin class' form method.
  */
 function system_plugin_ui_form($form, &$form_state, $plugin, $facet = NULL) {
-  $ui = system_plugin_manager('plugin_ui')->createInstance($plugin);
+  $ui = drupal_container()->get('plugin.manager.system.plugin_ui')->createInstance($plugin);
   $form = $ui->form($form, $form_state, $plugin, $facet);
   return $form;
 }
@@ -1154,7 +1154,7 @@ function system_plugin_ui_form_submit($form, &$form_state) {
  */
 function system_plugin_autocomplete($plugin_id, $string = '') {
   $matches = array();
-  $ui = system_plugin_manager('plugin_ui')->getDefinition($plugin_id);
+  $ui = drupal_container()->get('plugin.manager.system.plugin_ui')->getDefinition($plugin_id);
   $manager = new $ui['manager']();
   if ($string) {
     $plugins = $manager->getDefinitions();
@@ -1172,23 +1172,16 @@ function system_plugin_autocomplete($plugin_id, $string = '') {
  * A simple wrapper function for proxying to the plugin class' access method.
  */
 function system_plugin_ui_access($plugin, $facet = NULL) {
-  $ui = system_plugin_manager('plugin_ui')->createInstance($plugin);
+  $ui = drupal_container()->get('plugin.manager.system.plugin_ui')->createInstance($plugin);
   return $ui->access($plugin, $facet);
 }
 
 /**
- * A simple function for retreiving system plugin type managers from the DIC.
- */
-function system_plugin_manager($plugin_type) {
-  return drupal_container()->get("plugin.manager.system.$plugin_type");
-}
-
-/**
  * Implements hook_forms().
  */
 function system_forms() {
   $forms = array();
-  foreach (system_plugin_manager('plugin_ui')->getDefinitions() as $plugin_id => $plugin) {
+  foreach (drupal_container()->get('plugin.manager.system.plugin_ui')->getDefinitions() as $plugin_id => $plugin) {
     if (empty($forms[$plugin['id']])) {
       $forms[$plugin['id']]['callback'] = 'system_plugin_ui_form';
     }