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
@@ -151,17 +151,22 @@
 
         // 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']);
+
       }
       $profile_list[$profile] = $profile;
       $info['profile_list'] = $profile_list;
diff -u b/core/modules/system/src/Form/ModulesUninstallForm.php b/core/modules/system/src/Form/ModulesUninstallForm.php
--- b/core/modules/system/src/Form/ModulesUninstallForm.php
+++ b/core/modules/system/src/Form/ModulesUninstallForm.php
@@ -143,11 +143,10 @@
         $form['uninstall'][$module->getName()]['#disabled'] = TRUE;
       }
       // All modules which depend on this one must be uninstalled first, before
-      // we can allow this module to be uninstalled. (The installation profile
-      // is excluded from this list.)
-      $dependents = array_diff_key($module->required_by, $profiles);
-      foreach (array_keys($dependents) as $dependent) {
-        if (drupal_get_installed_schema_version($dependent) != SCHEMA_UNINSTALLED) {
+      // we can allow this module to be uninstalled. (Installation profiles are
+      // excluded from this list.)
+      foreach (array_keys($module->required_by) as $dependent) {
+        if (!in_array($dependent, array_keys($profiles)) && drupal_get_installed_schema_version($dependent) != SCHEMA_UNINSTALLED) {
           $name = isset($modules[$dependent]->info['name']) ? $modules[$dependent]->info['name'] : $dependent;
           $form['modules'][$module->getName()]['#required_by'][] = $name;
           $form['uninstall'][$module->getName()]['#disabled'] = TRUE;
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';
+      }
     }
   }
 
diff -u b/core/profiles/testing_inherited/tests/src/Functional/InheritedProfileTest.php b/core/profiles/testing_inherited/tests/src/Functional/InheritedProfileTest.php
--- b/core/profiles/testing_inherited/tests/src/Functional/InheritedProfileTest.php
+++ b/core/profiles/testing_inherited/tests/src/Functional/InheritedProfileTest.php
@@ -21,7 +21,7 @@
   /**
    * Tests inherited installation profile.
    */
-  function testInheritedProfile() {
+  public function testInheritedProfile() {
     // Check that the stable_login block exists.
     $this->assertInstanceOf(BlockInterface::class, Block::load('stable_login'));
 
only in patch2:
unchanged:
--- a/core/lib/Drupal/Core/EventSubscriber/ConfigImportSubscriber.php
+++ b/core/lib/Drupal/Core/EventSubscriber/ConfigImportSubscriber.php
@@ -111,16 +111,24 @@ protected function validateModules(ConfigImporter $config_importer) {
       }
     }
 
-    // Get the install profile from the site's configuration.
+    // Get the active install profile from the site's configuration.
     $current_core_extension = $config_importer->getStorageComparer()->getTargetStorage()->read('core.extension');
-    $install_profile = isset($current_core_extension['profile']) ? $current_core_extension['profile'] : NULL;
+    if (isset($current_core_extension['profile'])) {
+      // Ensure the active profile is not changing.
+      if ($current_core_extension['profile'] !== $core_extension['profile']) {
+        $config_importer->logError($this->t('Cannot change the install profile from %new_profile to %profile once Drupal is installed.', ['%profile' => $install_profile, '%new_profile' => $core_extension['profile']]));
+      }
+    }
+
+    // Get a list of installed profiles.
+    $installed_profiles = \Drupal::service('profile_handler')->getProfiles();
 
     // Ensure that all modules being uninstalled are not required by modules
     // that will be installed after the import.
     $uninstalls = $config_importer->getExtensionChangelist('module', 'uninstall');
     foreach ($uninstalls as $module) {
       foreach (array_keys($module_data[$module]->required_by) as $dependent_module) {
-        if ($module_data[$dependent_module]->status && !in_array($dependent_module, $uninstalls, TRUE) && $dependent_module !== $install_profile) {
+        if ($module_data[$dependent_module]->status && !in_array($dependent_module, $uninstalls, TRUE) && (!array_key_exists($dependent_module, $installed_profiles))) {
           $module_name = $module_data[$module]->info['name'];
           $dependent_module_name = $module_data[$dependent_module]->info['name'];
           $config_importer->logError($this->t('Unable to uninstall the %module module since the %dependent_module module is installed.', ['%module' => $module_name, '%dependent_module' => $dependent_module_name]));
@@ -128,15 +136,17 @@ protected function validateModules(ConfigImporter $config_importer) {
       }
     }
 
-    // Ensure that the install profile is not being uninstalled.
-    if (in_array($install_profile, $uninstalls, TRUE)) {
-      $profile_name = $module_data[$install_profile]->info['name'];
-      $config_importer->logError($this->t('Unable to uninstall the %profile profile since it is the install profile.', ['%profile' => $profile_name]));
-    }
-
-    // Ensure the profile is not changing.
-    if ($install_profile !== $core_extension['profile']) {
-      $config_importer->logError($this->t('Cannot change the install profile from %new_profile to %profile once Drupal is installed.', ['%profile' => $install_profile, '%new_profile' => $core_extension['profile']]));
+    // Ensure that none of the installed profiles are being uninstalled.
+    if ($profile_uninstalls = array_intersect_key($installed_profiles, array_flip($uninstalls))) {
+      foreach ($profile_uninstalls as $profile) {
+        $profile_names[] = $profile->info['name'];
+      }
+      $message = $this->formatPlural(count($profile_names),
+        'Unable to uninstall the %profile profile since it is an installed profile.',
+        'Unable to uninstall the %profile profiles since they are installed profiles.',
+        ['%profile' => implode(', ', $profile_names)]
+      );
+      $config_importer->logError($message);
     }
   }
 
only in patch2:
unchanged:
--- a/core/lib/Drupal/Core/Extension/ModuleInstaller.php
+++ b/core/lib/Drupal/Core/Extension/ModuleInstaller.php
@@ -330,7 +330,7 @@ public function uninstall(array $module_list, $uninstall_dependents = TRUE) {
     if ($uninstall_dependents) {
       // Add dependent modules to the list. The new modules will be processed as
       // the while loop continues.
-      $profile = drupal_get_profile();
+      $profiles = \Drupal::service('profile_handler')->getProfiles();
       while (list($module) = each($module_list)) {
         foreach (array_keys($module_data[$module]->required_by) as $dependent) {
           if (!isset($module_data[$dependent])) {
@@ -338,8 +338,8 @@ public function uninstall(array $module_list, $uninstall_dependents = TRUE) {
             return FALSE;
           }
 
-          // Skip already uninstalled modules.
-          if (isset($installed_modules[$dependent]) && !isset($module_list[$dependent]) && $dependent != $profile) {
+          // Skip already uninstalled modules and dependencies of profiles.
+          if (isset($installed_modules[$dependent]) && !isset($module_list[$dependent]) && (!array_key_exists($dependent, $profiles))) {
             $module_list[$dependent] = $dependent;
           }
         }
only in patch2:
unchanged:
--- a/core/modules/config/src/Tests/ConfigImportInstallProfileTest.php
+++ b/core/modules/config/src/Tests/ConfigImportInstallProfileTest.php
@@ -56,7 +56,7 @@ public function testInstallProfileValidation() {
 
     $this->drupalPostForm('admin/config/development/configuration', [], t('Import all'));
     $this->assertText('The configuration cannot be imported because it failed validation for the following reasons:');
-    $this->assertText('Unable to uninstall the Testing config import profile since it is the install profile.');
+    $this->assertText('Unable to uninstall the Testing config import profile since it is an installed profile.');
 
     // Uninstall dependencies of testing_config_import.
     $core['module']['testing_config_import'] = 0;