diff --git a/core/includes/update.inc b/core/includes/update.inc
index 5f0abf6..afe2122 100644
--- a/core/includes/update.inc
+++ b/core/includes/update.inc
@@ -156,7 +156,7 @@ function update_prepare_d8_bootstrap() {
         'description' => 'Please 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_extra_requirements($requirements);
+    update_migrate_requirements($requirements);
   }
   // Moves install_profile from variable to settings. You can't do that in
   // system.install because _system_rebuild_module_data() needs the profile
diff --git a/core/update.php b/core/update.php
index a254c17..e346f95 100644
--- a/core/update.php
+++ b/core/update.php
@@ -297,6 +297,18 @@ function update_extra_requirements($requirements = NULL) {
 }
 
 /**
+ * Returns and stores migration requirements that apply during the
+ * update process.
+ */
+function update_migrate_requirements($requirements = NULL) {
+  static $migrate_requirements = array();
+  if (isset($requirements)) {
+    $migrate_requirements += $requirements;
+  }
+  return $migrate_requirements;
+}
+
+/**
  * Checks update requirements and reports errors and (optionally) warnings.
  *
  * @param $skip_warnings
@@ -305,9 +317,13 @@ function update_extra_requirements($requirements = NULL) {
  *   FALSE.
  */
 function update_check_requirements($skip_warnings = FALSE) {
-  // Check requirements of all loaded modules.
-  $requirements = \Drupal::moduleHandler()->invokeAll('requirements', array('update'));
-  $requirements += update_extra_requirements();
+  // 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