diff --git a/core/includes/update.inc b/core/includes/update.inc
index 5a567f4..554fb3d 100644
--- a/core/includes/update.inc
+++ b/core/includes/update.inc
@@ -72,6 +72,107 @@ function update_check_incompatibility($name, $type = 'module') {
 }
 
 /**
+ * Returns whether the settings file requirement has been satisfied.
+ *
+ * @return array
+ *  A requirements info array.
+ */
+function update_settings_file_requirements() {
+  $requirements = array();
+
+  // Check whether settings.php needs to be rewritten.
+  $settings_file = conf_path() . '/settings.php';
+  $writable = drupal_verify_install_file($settings_file, FILE_EXIST | FILE_READABLE | FILE_WRITABLE);
+  $requirements['settings file']['title'] = 'Settings file';
+  if ($writable) {
+    $requirements['settings file'] += array(
+      'value' => 'settings.php is writable.',
+    );
+  }
+  else {
+    $requirements['settings file'] += array(
+      'value' => 'settings.php is not writable.',
+      'severity' => REQUIREMENT_ERROR,
+      'description' => 'Drupal requires write permissions to <em>' . $settings_file . '</em> during the update process. If you are unsure how to grant file permissions, consult the <a href="http://drupal.org/server-permissions">online handbook</a>.',
+    );
+  }
+  return $requirements;
+}
+
+/**
+ * Checks whether the minimum system schema version has been satisfied.
+ *
+ * Upgrading from a 7.x site database should block the update process.
+ * Ensure that the site is running Drupal 8 before proceeding. Not that this
+ * has to happen AFTER the database bootstraps because of
+ * drupal_get_installed_schema_version().
+ *
+ * @return array
+ *  A requirements info array.
+ */
+function update_migrate_requirements() {
+  $requirements = array();
+  try {
+    $system_schema = drupal_get_installed_schema_version('system');
+  }
+  catch (\Exception $e) {
+    $system_schema = db_query('SELECT schema_version FROM {system} WHERE name = :system', array(':system' => 'system'))->fetchField();
+  }
+  if ($system_schema < \Drupal::CORE_MINIMUM_SCHEMA_VERSION) {
+    $requirements = array(
+      'drupal 7 version' => array(
+        'title' => 'Drupal 7 version',
+        'value' => 'Your site database is from a Drupal 7 or earlier site.',
+        'severity' => REQUIREMENT_ERROR,
+        'description' => 'Migrate your Drupal 7 installation to a Drupal 8 installation using the Migrate module. Updating directly from Drupal 7 to Drupal 8 is not supported.',
+      ),
+    );
+  }
+  return $requirements;
+}
+
+/**
+ * Checks update requirements and reports errors and (optionally) warnings.
+ *
+ * @param $skip_warnings
+ *   (optional) If set to TRUE, requirement warnings will be ignored, and a
+ *   report will only be issued if there are requirement errors. Defaults to
+ *   FALSE.
+ */
+function update_check_requirements($skip_warnings = FALSE) {
+  // Upgrading from a 7.x site database should block the update process.
+  $requirements = update_migrate_requirements();
+  // If the user is not upgrading for a system schema prior to 8.x, gather
+  // any additional extra requirements.
+  if (empty($requirements)) {
+    // Check requirements of all loaded modules.
+    $requirements = \Drupal::moduleHandler()->invokeAll('requirements', array('update'));
+    $requirements += update_settings_file_requirements();
+  }
+  $severity = drupal_requirements_severity($requirements);
+
+  // If there are errors, always display them. If there are only warnings, skip
+  // them if the caller has indicated they should be skipped.
+  if ($severity == REQUIREMENT_ERROR || ($severity == REQUIREMENT_WARNING && !$skip_warnings)) {
+    update_task_list('requirements');
+    drupal_set_title('Requirements problem');
+    $status = array(
+      '#theme' => 'status_report',
+      '#requirements' => $requirements,
+    );
+    $status_report = drupal_render($status);
+    $status_report .= 'Check the messages and <a href="' . check_url(drupal_requirements_url($severity)) . '">try again</a>.';
+    drupal_add_http_header('Content-Type', 'text/html; charset=utf-8');
+    $maintenance_page = array(
+      '#theme' => 'maintenance_page',
+      '#content' => $status_report,
+    );
+    print drupal_render($maintenance_page);
+    exit();
+  }
+}
+
+/**
  * Performs extra steps required to bootstrap when using a Drupal 7 database.
  *
  * Users who still have a Drupal 7 database (and are in the process of
@@ -111,27 +212,6 @@ function update_prepare_d8_bootstrap() {
   $kernel = new DrupalKernel('update', drupal_classloader(), FALSE);
   $kernel->boot();
 
-  // If any of the required settings needs to be written, then settings.php
-  // needs to be writable.
-  if (!$settings_exist) {
-    $settings_file = conf_path() . '/settings.php';
-    $writable = drupal_verify_install_file($settings_file, FILE_EXIST | FILE_READABLE | FILE_WRITABLE);
-    $requirements['settings file']['title'] = 'Settings file';
-    if ($writable) {
-      $requirements['settings file'] += array(
-        'value' => 'settings.php is writable.',
-      );
-    }
-    else {
-      $requirements['settings file'] += array(
-        'value' => 'settings.php is not writable.',
-        'severity' => REQUIREMENT_ERROR,
-        'description' => 'Drupal requires write permissions to <em>' . $settings_file . '</em> during the update process. If you are unsure how to grant file permissions, consult the <a href="http://drupal.org/server-permissions">online handbook</a>.',
-      );
-    }
-    update_extra_requirements($requirements);
-  }
-
   // Bootstrap the database.
   require_once __DIR__ . '/database.inc';
 
@@ -139,26 +219,6 @@ function update_prepare_d8_bootstrap() {
   // below.
   require_once __DIR__ . '/module.inc';
 
-  // Ensure that the site is running Drupal 8 before proceeding. Not that this
-  // has to happen AFTER the database bootstraps because of
-  // drupal_get_installed_schema_version().
-  try {
-    $system_schema = drupal_get_installed_schema_version('system');
-  }
-  catch (\Exception $e) {
-    $system_schema = db_query('SELECT schema_version FROM {system} WHERE name = :system', array(':system' => 'system'))->fetchField();
-  }
-  if ($system_schema < \Drupal::CORE_MINIMUM_SCHEMA_VERSION) {
-    $requirements = array(
-      'drupal 7 version' => array(
-        'title' => 'Drupal 7 version',
-        'value' => 'Your site database is from a Drupal 7 or earlier site.',
-        'severity' => REQUIREMENT_ERROR,
-        'description' => 'Migrate your Drupal 7 installation to a Drupal 8 installation using the Migrate module. Updating directly from Drupal 7 to Drupal 8 is not supported.',
-      ),
-    );
-    update_migrate_requirements($requirements);
-  }
   // Moves install_profile from variable to settings. You can't do that in
   // system.install because _system_rebuild_module_data() needs the profile
   // directly. Check that it has not been set already. This is the case for
diff --git a/core/update.php b/core/update.php
index 5983cbd..dd301cf 100644
--- a/core/update.php
+++ b/core/update.php
@@ -285,71 +285,6 @@ function update_task_list($active = NULL) {
   drupal_add_region_content('sidebar_first', drupal_render($task_list));
 }
 
-/**
- * Returns and stores extra requirements that apply during the update process.
- */
-function update_extra_requirements($requirements = NULL) {
-  $extra_requirements = &drupal_static(__FUNCTION__);
-  if (!isset($extra_requirements)) {
-    $extra_requirements = array();
-  }
-  $extra_requirements += $requirements;
-  return $extra_requirements;
-}
-
-/**
- * Returns and stores migration requirements that apply during the
- * update process.
- */
-function update_migrate_requirements($requirements = array()) {
-  $migrate_requirements = &drupal_static(__FUNCTION__);
-  if (!isset($migrate_requirements)) {
-    $migrate_requirements = array();
-  }
-  $migrate_requirements += $requirements;
-  return $migrate_requirements;
-}
-
-/**
- * Checks update requirements and reports errors and (optionally) warnings.
- *
- * @param $skip_warnings
- *   (optional) If set to TRUE, requirement warnings will be ignored, and a
- *   report will only be issued if there are requirement errors. Defaults to
- *   FALSE.
- */
-function update_check_requirements($skip_warnings = FALSE) {
-  // Upgrading from a 7.x site database should block the update process.
-  $requirements = update_migrate_requirements();
-  if (empty($requirements)) {
-    // Check requirements of all loaded modules.
-    $requirements = \Drupal::moduleHandler()->invokeAll('requirements', array('update'));
-    $requirements += update_extra_requirements();
-  }
-  $severity = drupal_requirements_severity($requirements);
-
-  // If there are errors, always display them. If there are only warnings, skip
-  // them if the caller has indicated they should be skipped.
-  if ($severity == REQUIREMENT_ERROR || ($severity == REQUIREMENT_WARNING && !$skip_warnings)) {
-    update_task_list('requirements');
-    drupal_set_title('Requirements problem');
-    $status = array(
-      '#theme' => 'status_report',
-      '#requirements' => $requirements,
-    );
-    $status_report = drupal_render($status);
-    $status_report .= 'Check the messages and <a href="' . check_url(drupal_requirements_url($severity)) . '">try again</a>.';
-    drupal_add_http_header('Content-Type', 'text/html; charset=utf-8');
-    $maintenance_page = array(
-      '#theme' => 'maintenance_page',
-      '#content' => $status_report,
-    );
-    print drupal_render($maintenance_page);
-    exit();
-  }
-}
-
-
 // Some unavoidable errors happen because the database is not yet up-to-date.
 // Our custom error handler is not yet installed, so we just suppress them.
 ini_set('display_errors', FALSE);
@@ -403,6 +338,8 @@ function update_check_requirements($skip_warnings = FALSE) {
 
   // Check the update requirements for Drupal. Only report on errors at this
   // stage, since the real requirements check happens further down.
+  // The request will exit() if any requirement violations are reported in the
+  // following function invocation.
   update_check_requirements(TRUE);
 
   // Redirect to the update information page if all requirements were met.