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
@@ -151,19 +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'], $base_info['themes']));
-
         if (isset($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']);