diff -u b/core/lib/Drupal/Core/Extension/ProfileHandler.php b/core/lib/Drupal/Core/Extension/ProfileHandler.php
--- b/core/lib/Drupal/Core/Extension/ProfileHandler.php
+++ b/core/lib/Drupal/Core/Extension/ProfileHandler.php
@@ -158,10 +158,15 @@
 
         // Ensure all themes are cleanly merged.
         $info['themes'] = array_unique(array_merge($info['themes'], $base_info['themes']));
-        // Apply excluded themes.
-        $info['themes'] = array_diff($info['themes'], $info['base profile']['excluded_themes']);
+
+        if (isset($info['base profile']['excluded_themes'])) {
+          // Apply excluded themes.
+          $info['themes'] = array_diff($info['themes'], $info['base profile']['excluded_themes']);
+        }
+        
         // Ensure each theme is listed only once.
         $info['themes'] = array_unique($info['themes']);
+
       }
       $profile_list[$profile] = $profile;
       $info['profile_list'] = $profile_list;
diff -u b/core/modules/system/system.module b/core/modules/system/system.module
--- b/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -1044,15 +1044,17 @@
   }
 
   // This must be done after _system_rebuild_module_data_ensure_required().
-  $profile = drupal_get_profile();
-  if ($profile && isset($modules[$profile])) {
-    // The installation profile is required, if it's a valid module.
-    $modules[$profile]->info['required'] = TRUE;
-    // Add a default distribution name if the profile did not provide one.
-    // @see install_profile_info()
-    // @see drupal_install_profile_distribution_name()
-    if (!isset($modules[$profile]->info['distribution']['name'])) {
-      $modules[$profile]->info['distribution']['name'] = 'Drupal';
+  $profiles = \Drupal::service('profile_handler')->getProfiles();
+  foreach ($profiles as $profile_name => $profile) {
+    if (isset($modules[$profile_name])) {
+      // Installation profiles are required, if it's a valid module.
+      $modules[$profile_name]->info['required'] = TRUE;
+      // Add a default distribution name if the profile did not provide one.
+      // @see install_profile_info()
+      // @see drupal_install_profile_distribution_name()
+      if (!isset($modules[$profile_name]->info['distribution']['name'])) {
+        $modules[$profile_name]->info['distribution']['name'] = 'Drupal';
+      }
     }
   }