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
@@ -151,15 +151,19 @@
 
         // Ensure all dependencies are cleanly merged.
         $info['dependencies'] = array_merge($info['dependencies'], $base_info['dependencies']);
-        // Apply excluded dependencies.
-        $info['dependencies'] = array_diff($info['dependencies'], $info['base profile']['excluded_dependencies']);
+        if (isset($info['base profile']['excluded_dependencies'])) {
+          // Apply excluded dependencies.
+          $info['dependencies'] = array_diff($info['dependencies'], $info['base profile']['excluded_dependencies']);
+        }
         // Ensure there's no circular dependency.
         $info['dependencies'] = array_diff($info['dependencies'], [$profile]);
 
         // 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']);
       }
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
@@ -950,13 +950,27 @@
 function _system_rebuild_module_data() {
   $listing = new ExtensionDiscovery(\Drupal::root());
 
+  // Find installation profiles. This needs to happen before performing a
+  // module scan as the module scan requires knowing what the active profile is.
+  // @todo Remove as part of https://www.drupal.org/node/2186491.
+  $profiles = $listing->scan('profile');
+  $profile = drupal_get_profile();
+  if ($profile && isset($profiles[$profile])) {
+    // Prime the drupal_get_filename() static cache with the profile info file
+    // location so we can use drupal_get_path() on the active profile during
+    // the module scan.
+    // @todo Remove as part of https://www.drupal.org/node/2186491.
+    drupal_get_filename('profile', $profile, $profiles[$profile]->getPathname());
+  }
+
   // Find modules.
   $modules = $listing->scan('module');
-
-  // Find profiles.
-  /** @var \Drupal\Core\Extension\ProfileHandlerInterface $profile_handler */
-  $profile_handler = \Drupal::service('profile_handler');
-  $modules = array_merge($modules, $profile_handler->getProfiles());
+  // Include the installation profile in modules that are loaded.
+  if ($profile) {
+    $modules[$profile] = $profiles[$profile];
+    // Installation profile hooks are always executed last.
+    $modules[$profile]->weight = 1000;
+  }
 
   // Set defaults for module info.
   $defaults = array(
@@ -970,14 +984,7 @@
   // Read info files for each module.
   foreach ($modules as $key => $module) {
     // Look for the info file.
-    // @todo On the longrun we should leverage the extension lists services,
-    //    see https://www.drupal.org/node/2208429.
-    if ($module->getType() === 'profile') {
-      $module->info = $profile_handler->getProfileInfo($module->getName());
-    }
-    else {
-      $module->info = \Drupal::service('info_parser')->parse($module->getPathname());
-    }
+    $module->info = \Drupal::service('info_parser')->parse($module->getPathname());
 
     // Add the info file modification time, so it becomes available for
     // contributed modules to use for ordering module lists.
@@ -987,27 +994,13 @@
 function _system_rebuild_module_data() {
   $listing = new ExtensionDiscovery(\Drupal::root());
 
-  // Find installation profiles. This needs to happen before performing a
-  // module scan as the module scan requires knowing what the active profile is.
-  // @todo Remove as part of https://www.drupal.org/node/2186491.
-  $profiles = $listing->scan('profile');
-  $profile = drupal_get_profile();
-  if ($profile && isset($profiles[$profile])) {
-    // Prime the drupal_get_filename() static cache with the profile info file
-    // location so we can use drupal_get_path() on the active profile during
-    // the module scan.
-    // @todo Remove as part of https://www.drupal.org/node/2186491.
-    drupal_get_filename('profile', $profile, $profiles[$profile]->getPathname());
-  }
-
   // Find modules.
   $modules = $listing->scan('module');
-  // Include the installation profile in modules that are loaded.
-  if ($profile) {
-    $modules[$profile] = $profiles[$profile];
-    // Installation profile hooks are always executed last.
-    $modules[$profile]->weight = 1000;
-  }
+
+  // Find profiles.
+  /** @var \Drupal\Core\Extension\ProfileHandlerInterface $profile_handler */
+  $profile_handler = \Drupal::service('profile_handler');
+  $modules = array_merge($modules, $profile_handler->getProfiles());
 
   // Set defaults for module info.
   $defaults = array(
@@ -1021,7 +1014,14 @@
   // Read info files for each module.
   foreach ($modules as $key => $module) {
     // Look for the info file.
-    $module->info = \Drupal::service('info_parser')->parse($module->getPathname());
+    // @todo On the longrun we should leverage the extension lists services,
+    //    see https://www.drupal.org/node/2208429.
+    if ($module->getType() === 'profile') {
+      $module->info = $profile_handler->getProfileInfo($module->getName());
+    }
+    else {
+      $module->info = \Drupal::service('info_parser')->parse($module->getPathname());
+    }
 
     // Add the info file modification time, so it becomes available for
     // contributed modules to use for ordering module lists.