reverted:
--- b/core/includes/config.inc
+++ a/core/includes/config.inc
@@ -41,10 +41,8 @@
  * @see \Drupal\Core\Config\ConfigInstaller
  */
 function config_install_default_config($type, $name) {
+  // Get all default configuration owned by this extension.
+  $source_storage = new ExtensionInstallStorage();
-  // Get all default configuration owned by this extension. During installation
-  // this should include config from the installation profile. During normal
-  // runtime the installation profile should be ignored.
-  $source_storage = new ExtensionInstallStorage(drupal_get_profile(), drupal_installation_attempted());
   $config_to_install = $source_storage->listAll($name . '.');
 
   // Work out if this extension provides default configuration for any other
diff -u b/core/includes/update.inc b/core/includes/update.inc
--- b/core/includes/update.inc
+++ b/core/includes/update.inc
@@ -374,7 +374,7 @@
         }
 
         if ($record->type == 'module') {
-          if (isset($module_data[$record->name])) {
+          if ($record->status && isset($module_data[$record->name])) {
             $module_config->set('enabled.' . $record->name, $record->weight);
           }
         }
reverted:
--- b/core/lib/Drupal/Core/Config/ExtensionInstallStorage.php
+++ a/core/lib/Drupal/Core/Config/ExtensionInstallStorage.php
@@ -16,36 +16,6 @@
 class ExtensionInstallStorage extends InstallStorage {
 
   /**
-   * Include profile config directories
-   *.
-   * @var bool
-   */
-  protected $includeProfile;
-
-  /**
-   * The installation profile.
-   *
-   * @var string
-   */
-  protected $profile;
-
-  /**
-   * Constructs a new FileStorage controller.
-   *
-   * @param string $profile
-   *   The name of the installation profile used on the site.
-   * @param bool $include_profile
-   *   If TRUE, include default configuration from the installation profile's
-   *   config directory.
-   *
-   * Overrides Drupal\Core\Config\FileStorage::__construct().
-   */
-  public function __construct($profile, $include_profile = FALSE) {
-    $this->includeProfile = $include_profile;
-    $this->profile = $profile;
-  }
-
-  /**
    * Returns a map of all config object names and their folders.
    *
    * The list is based on enabled modules and themes.
@@ -55,13 +25,7 @@
    */
   protected function getAllFolders() {
     if (!isset($this->folders)) {
+      $this->folders = $this->getComponentNames('module', array_keys(\Drupal::moduleHandler()->getModuleList()));
-      $module_list = \Drupal::moduleHandler()->getModuleList();
-      // Only include the profile module's config if $this->includeProfile is
-      // set to TRUE.
-      if (!$this->includeProfile && isset($module_list[$this->profile])) {
-        unset($module_list[$this->profile]);
-      }
-      $this->folders = $this->getComponentNames('module', array_keys($module_list));
       $this->folders += $this->getComponentNames('theme', array_keys(array_filter(list_themes(), function ($theme) {return $theme->status;})));
     }
     return $this->folders;
diff -u b/core/modules/system/lib/Drupal/system/Tests/Upgrade/ModulesDisabledUpgradePathTest.php b/core/modules/system/lib/Drupal/system/Tests/Upgrade/ModulesDisabledUpgradePathTest.php
--- b/core/modules/system/lib/Drupal/system/Tests/Upgrade/ModulesDisabledUpgradePathTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Upgrade/ModulesDisabledUpgradePathTest.php
@@ -35,24 +35,20 @@
    */
   public function testDisabledUpgrade() {
-    $this->assertTrue($this->performUpgrade(), 'The upgrade was completed successfully.');
-
-    // Get enabled modules.
-    $enabled = \Drupal::moduleHandler()->getModuleList();
-    // Get all available modules.
-    $available = system_rebuild_module_data();
-    // Filter out hidden test modules.
-    foreach ($available as $module => $data) {
-      if (!empty($data->info['hidden'])) {
-        unset($available[$module]);
-      }
+    $modules = db_query('SELECT name, info FROM {system} WHERE type = :module AND status = 0 AND schema_version <> :schema_uninstalled', array(
+      ':module' => 'module',
+      ':schema_uninstalled' => SCHEMA_UNINSTALLED,
+    ))->fetchAllKeyed(0, 1);
+    array_walk($modules, function (&$value, $key) {
+      $info = unserialize($value);
+      $value = $info['name'];
+    });
+    // Load the first update screen.
+    $this->getUpdatePhp();
+    if (!$this->assertResponse(200)) {
+      throw new \Exception('Initial GET to update.php did not return HTTP 200 status.');
     }
-    $to_enable = array_diff_key($available, $enabled);
-    \Drupal::moduleHandler()->install(array_keys($to_enable));
-    // Check for updates.
-    require_once DRUPAL_ROOT . '/core/includes/update.inc';
-    require_once DRUPAL_ROOT . '/core/includes/install.inc';
-    $updates = update_get_update_list();
-    $this->assertEqual($updates, array(), 'No pending updates after enabling all modules.');
-    $this->assertTrue(\Drupal::state()->get('update_test_1_update_dependencies_run'), 'Module update dependencies resolved for disabled modules');
+    $this->assertNoFieldByXPath('//input[@type="submit"]', NULL, 'No continue button found on update.php.');
+    $this->assertText('Drupal 8 no longer supports disabled modules. Please either enable or uninstall them before upgrading.');
+    $this->assertText(implode(', ', $modules));
   }
 }
diff -u b/core/modules/system/system.install b/core/modules/system/system.install
--- b/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -513,6 +513,25 @@
     $requirements['update status']['title'] = t('Update notifications');
   }
 
+  // Ensure that if upgrading from 7 to 8 we have no disabled modules.
+  if ($phase == 'update' && db_table_exists('system')) {
+    $modules = db_query('SELECT name, info FROM {system} WHERE type = :module AND status = 0 AND schema_version <> :schema_uninstalled', array(
+      ':module' => 'module',
+      ':schema_uninstalled' => SCHEMA_UNINSTALLED,
+    ))->fetchAllKeyed(0, 1);
+    array_walk($modules, function (&$value, $key) {
+      $info = unserialize($value);
+      $value = $info['name'];
+    });
+    if (!empty($modules)) {
+      $requirements['disabled_modules'] = array(
+        'severity' => REQUIREMENT_ERROR,
+        'title' => t('Disabled modules'),
+        'value' => format_plural(count($modules), 'The %modules module is disabled.', 'The following modules are disabled: %modules', array('%modules' => implode(', ', $modules))),
+        'description' => t('Drupal 8 no longer supports disabled modules. Please either enable or uninstall them before upgrading.'),
+      );
+    }
+  }
   return $requirements;
 }