diff -u b/core/lib/Drupal/Core/Extension/RequiredModuleUninstallValidator.php b/core/lib/Drupal/Core/Extension/RequiredModuleUninstallValidator.php
--- b/core/lib/Drupal/Core/Extension/RequiredModuleUninstallValidator.php
+++ b/core/lib/Drupal/Core/Extension/RequiredModuleUninstallValidator.php
@@ -34,7 +34,7 @@
     $reasons = [];
     $module_info = $this->getModuleInfoByModule($module);
     if (!empty($module_info['required'])) {
-      $reasons[] = $this->t('The @module module is required.', ['@module' => $module_info['name']]);
+      $reasons[] = $this->t('The @module module is required', ['@module' => $module_info['name']]);
     }
     return $reasons;
   }
diff -u b/core/modules/book/book.module b/core/modules/book/book.module
--- b/core/modules/book/book.module
+++ b/core/modules/book/book.module
@@ -19,7 +19,6 @@
 use Drupal\Core\Language\LanguageInterface;
 use Drupal\Core\Entity\Display\EntityViewDisplayInterface;
 use Drupal\Core\Template\Attribute;
-use Drupal\Core\Extension\Extension;
 
 /**
  * Implements hook_help().
diff -u b/core/modules/book/src/BookUninstallValidator.php b/core/modules/book/src/BookUninstallValidator.php
--- b/core/modules/book/src/BookUninstallValidator.php
+++ b/core/modules/book/src/BookUninstallValidator.php
@@ -57,13 +57,13 @@
     $reasons = [];
     if ($module == 'book') {
       if ($this->hasBookOutlines()) {
-        $reasons[] = $this->t('To uninstall Book, delete all content that is part of a book.');
+        $reasons[] = $this->t('To uninstall Book, delete all content that is part of a book');
       }
       else {
         // The book node type is provided by the Book module. Prevent uninstall
         // if there are any nodes of that type.
         if ($this->hasBookNodes()) {
-          $reasons[] = $this->t('To uninstall Book, delete all content that has the Book content type.');
+          $reasons[] = $this->t('To uninstall Book, delete all content that has the Book content type');
         }
       }
     }
diff -u /dev/null b/core/modules/book/src/Tests/BookUninstallTest.php
--- /dev/null
+++ b/core/modules/book/src/Tests/BookUninstallTest.php
@@ -0,0 +1,99 @@
+<?php
+
+/**
+ * @file
+ * Contains Drupal\book\Tests\BookUninstallTest.
+ */
+
+namespace Drupal\book\Tests;
+
+use Drupal\node\Entity\Node;
+use Drupal\node\Entity\NodeType;
+use Drupal\simpletest\KernelTestBase;
+
+/**
+ * Tests that the Book module cannot be uninstalled if books exist.
+ *
+ * @group book
+ */
+class BookUninstallTest extends KernelTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = array('system', 'user', 'field', 'filter', 'text', 'entity_reference', 'node', 'book');
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+    $this->installEntitySchema('user');
+    $this->installEntitySchema('node');
+    $this->installSchema('book', array('book'));
+    $this->installSchema('node', array('node_access'));
+    $this->installConfig(array('node', 'book', 'field'));
+    // For uninstall to work.
+    $this->installSchema('user', array('users_data'));
+  }
+
+  /**
+   * Tests the book_system_info_alter() method.
+   */
+  public function testBookUninstall() {
+    // No nodes exist.
+    $validation_reasons = \Drupal::service('module_installer')->validateUninstall(['book']);
+    $this->assertEqual([], $validation_reasons, 'The book module is not required.');
+
+    $content_type = NodeType::create(array(
+      'type' => $this->randomMachineName(),
+      'name' => $this->randomString(),
+    ));
+    $content_type->save();
+    $book_config = $this->config('book.settings');
+    $allowed_types = $book_config->get('allowed_types');
+    $allowed_types[] = $content_type->id();
+    $book_config->set('allowed_types', $allowed_types)->save();
+
+    $node = Node::create(array('type' => $content_type->id()));
+    $node->book['bid'] = 'new';
+    $node->save();
+
+    // One node in a book but not of type book.
+    $validation_reasons = \Drupal::service('module_installer')->validateUninstall(['book']);
+    $this->assertEqual(['To uninstall Book, delete all content that is part of a book'], $validation_reasons['book']);
+
+    $book_node = Node::create(array('type' => 'book'));
+    $book_node->book['bid'] = FALSE;
+    $book_node->save();
+
+    // Two nodes, one in a book but not of type book and one book node (which is
+    // not in a book).
+    $validation_reasons = \Drupal::service('module_installer')->validateUninstall(['book']);
+    $this->assertEqual(['To uninstall Book, delete all content that is part of a book'], $validation_reasons['book']);
+
+    $node->delete();
+    // One node of type book but not actually part of a book.
+    $validation_reasons = \Drupal::service('module_installer')->validateUninstall(['book']);
+    $this->assertEqual(['To uninstall Book, delete all content that has the Book content type'], $validation_reasons['book']);
+
+    $book_node->delete();
+    // No nodes exist therefore the book module is not required.
+    $module_data = _system_rebuild_module_data();
+    $this->assertFalse(isset($module_data['book']->info['required']), 'The book module is not required.');
+
+    $node = Node::create(array('type' => $content_type->id()));
+    $node->save();
+    // One node exists but is not part of a book therefore the book module is
+    // not required.
+    $validation_reasons = \Drupal::service('module_installer')->validateUninstall(['book']);
+    $this->assertEqual([], $validation_reasons, 'The book module is not required.');
+
+    // Uninstall the Book module and check the node type is deleted.
+    \Drupal::service('module_installer')->uninstall(array('book'));
+    $this->assertNull(NodeType::load('book'), "The book node type does not exist.");
+  }
+
+}
diff -u b/core/modules/book/tests/src/Unit/BookUninstallValidatorTest.php b/core/modules/book/tests/src/Unit/BookUninstallValidatorTest.php
--- b/core/modules/book/tests/src/Unit/BookUninstallValidatorTest.php
+++ b/core/modules/book/tests/src/Unit/BookUninstallValidatorTest.php
@@ -76,7 +76,7 @@
       ->willReturn(TRUE);
 
     $module = 'book';
-    $expected = ['To uninstall Book, delete all content that has the Book content type.'];
+    $expected = ['To uninstall Book, delete all content that has the Book content type'];
     $reasons = $this->bookUninstallValidator->validate($module);
     $this->assertSame($expected, $reasons);
   }
@@ -92,7 +92,7 @@
       ->method('hasBookNodes');
 
     $module = 'book';
-    $expected = ['To uninstall Book, delete all content that is part of a book.'];
+    $expected = ['To uninstall Book, delete all content that is part of a book'];
     $reasons = $this->bookUninstallValidator->validate($module);
     $this->assertSame($expected, $reasons);
   }
diff -u b/core/modules/config/src/Tests/ConfigImportAllTest.php b/core/modules/config/src/Tests/ConfigImportAllTest.php
--- b/core/modules/config/src/Tests/ConfigImportAllTest.php
+++ b/core/modules/config/src/Tests/ConfigImportAllTest.php
@@ -8,8 +8,10 @@
 namespace Drupal\config\Tests;
 
 use Drupal\Core\Config\StorageComparer;
+use Drupal\filter\Entity\FilterFormat;
 use Drupal\system\Tests\Module\ModuleTestBase;
 use Drupal\shortcut\Entity\Shortcut;
+use Drupal\taxonomy\Entity\Term;
 
 /**
  * Tests the largest configuration import possible with all available modules.
@@ -83,12 +85,13 @@
     // Purge the data.
     field_purge_batch(1000);
 
-    // Delete any forum terms so it can be uninstalled.
-    $vid = $this->config('forum.settings')->get('vocabulary');
-    $terms = entity_load_multiple_by_properties('taxonomy_term', ['vid' => $vid]);
-    foreach ($terms as $term) {
-      $term->delete();
-    }
+    // Delete all terms.
+    $terms = Term::loadMultiple();
+    entity_delete_multiple('taxonomy_term', array_keys($terms));
+
+    // Delete all filter formats.
+    $filters = FilterFormat::loadMultiple();
+    entity_delete_multiple('filter_format', array_keys($filters));
 
     // Delete any shortcuts so the shortcut module can be uninstalled.
     $shortcuts = Shortcut::loadMultiple();
@@ -97,7 +100,11 @@
     system_list_reset();
     $all_modules = system_rebuild_module_data();
 
-    $modules_to_uninstall = array_filter($all_modules, function ($module) {
+    // Ensure that only core required modules and the install profile can not be uninstalled.
+    $validation_reasons = \Drupal::service('module_installer')->validateUninstall(array_keys($all_modules));
+    $this->assertEqual(['standard', 'system', 'user'], array_keys($validation_reasons));
+
+    $modules_to_uninstall = array_filter($all_modules, function ($module) use ($validation_reasons) {
       // Filter required and not enabled modules.
       if (!empty($module->info['required']) || $module->status == FALSE) {
         return FALSE;
@@ -108,14 +115,9 @@
     // Can not uninstall config and use admin/config/development/configuration!
     unset($modules_to_uninstall['config']);
 
-    // Can not uninstall Editor and Filter and their dependencies as they
-    // provide filter plugins that can not be removed.
-    unset($modules_to_uninstall['editor']);
-    unset($modules_to_uninstall['filter']);
-    unset($modules_to_uninstall['file']);
-    unset($modules_to_uninstall['field']);
-
     $this->assertTrue(isset($modules_to_uninstall['comment']), 'The comment module will be disabled');
+    $this->assertTrue(isset($modules_to_uninstall['file']), 'The File module will be disabled');
+    $this->assertTrue(isset($modules_to_uninstall['editor']), 'The Editor module will be disabled');
 
     // Uninstall all modules that can be uninstalled.
     \Drupal::service('module_installer')->uninstall(array_keys($modules_to_uninstall));
diff -u b/core/modules/field/field.module b/core/modules/field/field.module
--- b/core/modules/field/field.module
+++ b/core/modules/field/field.module
@@ -7,7 +7,6 @@
 use Drupal\Core\Config\ConfigImporter;
 use Drupal\Core\Entity\EntityTypeInterface;
 use Drupal\Core\Entity\DynamicallyFieldableEntityStorageInterface;
-use Drupal\Core\Extension\Extension;
 use Drupal\field\Entity\FieldConfig;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Routing\RouteMatchInterface;
diff -u b/core/modules/field/src/FieldUninstallValidator.php b/core/modules/field/src/FieldUninstallValidator.php
--- b/core/modules/field/src/FieldUninstallValidator.php
+++ b/core/modules/field/src/FieldUninstallValidator.php
@@ -55,10 +55,10 @@
         }
       }
       if ($non_deleted) {
-        $reasons[] = $this->t('Fields type(s) in use.');
+        $reasons[] = $this->t('Fields type(s) in use');
       }
       else {
-        $reasons[] = $this->t('Fields pending deletion.');
+        $reasons[] = $this->t('Fields pending deletion');
       }
     }
     return $reasons;
diff -u b/core/modules/field/tests/src/Unit/FieldUninstallValidatorTest.php b/core/modules/field/tests/src/Unit/FieldUninstallValidatorTest.php
--- b/core/modules/field/tests/src/Unit/FieldUninstallValidatorTest.php
+++ b/core/modules/field/tests/src/Unit/FieldUninstallValidatorTest.php
@@ -61,7 +61,7 @@
       ->willReturn([$field_storage]);
 
     $module = $this->randomMachineName();
-    $expected = ['Fields pending deletion.'];
+    $expected = ['Fields pending deletion'];
     $reasons = $this->fieldUninstallValidator->validate($module);
     $this->assertSame($expected, $reasons);
   }
@@ -81,7 +81,7 @@
       ->willReturn([$field_storage]);
 
     $module = $this->randomMachineName();
-    $expected = ['Fields type(s) in use.'];
+    $expected = ['Fields type(s) in use'];
     $reasons = $this->fieldUninstallValidator->validate($module);
     $this->assertSame($expected, $reasons);
   }
diff -u b/core/modules/filter/filter.module b/core/modules/filter/filter.module
--- b/core/modules/filter/filter.module
+++ b/core/modules/filter/filter.module
@@ -10,7 +10,6 @@
 use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Component\Utility\Xss;
 use Drupal\Core\Cache\Cache;
-use Drupal\Core\Extension\Extension;
 use Drupal\Core\Render\Element;
 use Drupal\Core\Routing\RouteMatchInterface;
 use Drupal\Core\Session\AccountInterface;
diff -u b/core/modules/filter/src/FilterUninstallValidator.php b/core/modules/filter/src/FilterUninstallValidator.php
--- b/core/modules/filter/src/FilterUninstallValidator.php
+++ b/core/modules/filter/src/FilterUninstallValidator.php
@@ -69,7 +69,7 @@
         }
       }
       if (!empty($used_in)) {
-        $reasons[] = $this->t('Provides a filter plugin that is in use in the following filter formats: %formats.', ['%formats' => implode(', ', $used_in)]);
+        $reasons[] = $this->t('Provides a filter plugin that is in use in the following filter formats: %formats', ['%formats' => implode(', ', $used_in)]);
       }
     }
     return $reasons;
diff -u b/core/modules/filter/tests/src/Unit/FilterUninstallValidatorTest.php b/core/modules/filter/tests/src/Unit/FilterUninstallValidatorTest.php
--- b/core/modules/filter/tests/src/Unit/FilterUninstallValidatorTest.php
+++ b/core/modules/filter/tests/src/Unit/FilterUninstallValidatorTest.php
@@ -160,7 +160,7 @@
       ]);
 
     $expected = [
-      SafeMarkup::format('Provides a filter plugin that is in use in the following filter formats: %formats.', ['%formats' => implode(', ', [
+      SafeMarkup::format('Provides a filter plugin that is in use in the following filter formats: %formats', ['%formats' => implode(', ', [
         'Filter Format 1 Label',
         'Filter Format 2 Label',
       ])]),
diff -u b/core/modules/forum/forum.module b/core/modules/forum/forum.module
--- b/core/modules/forum/forum.module
+++ b/core/modules/forum/forum.module
@@ -11,11 +11,8 @@
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Url;
 use Drupal\Component\Utility\SafeMarkup;
-use Drupal\Core\Extension\Extension;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Routing\RouteMatchInterface;
-use Drupal\taxonomy\Entity\Vocabulary;
-use Symfony\Component\Routing\Exception\RouteNotFoundException;
 use Drupal\user\Entity\User;
 
 /**
diff -u b/core/modules/forum/src/ForumUninstallValidator.php b/core/modules/forum/src/ForumUninstallValidator.php
--- b/core/modules/forum/src/ForumUninstallValidator.php
+++ b/core/modules/forum/src/ForumUninstallValidator.php
@@ -70,19 +70,19 @@
     $reasons = [];
     if ($module == 'forum') {
       if ($this->hasForumNodes()) {
-        $reasons[] = $this->t('To uninstall Forum, first delete all <em>Forum</em> content.');
+        $reasons[] = $this->t('To uninstall Forum, first delete all <em>Forum</em> content');
       }
 
       $vocabulary = $this->getForumVocabulary();
       if ($this->hasTermsForVocabulary($vocabulary)) {
         if ($vocabulary->access('view')) {
-          $reasons[] = $this->t('To uninstall Forum, first delete all <a href="!url">%vocabulary</a> terms.', [
+          $reasons[] = $this->t('To uninstall Forum, first delete all <a href="!url">%vocabulary</a> terms', [
             '%vocabulary' => $vocabulary->label(),
             '!url' => $vocabulary->url('overview-form'),
           ]);
         }
         else {
-          $reasons[] = $this->t('To uninstall Forum, first delete all %vocabulary terms.', [
+          $reasons[] = $this->t('To uninstall Forum, first delete all %vocabulary terms', [
             '%vocabulary' => $vocabulary->label()
           ]);
         }
diff -u b/core/modules/forum/src/Tests/ForumUninstallTest.php b/core/modules/forum/src/Tests/ForumUninstallTest.php
--- b/core/modules/forum/src/Tests/ForumUninstallTest.php
+++ b/core/modules/forum/src/Tests/ForumUninstallTest.php
@@ -74,7 +74,7 @@
     $this->drupalGet('admin/modules/uninstall');
     // Assert forum is required.
     $this->assertNoFieldByName('uninstall[forum]');
-    $this->assertText('To uninstall Forum, first delete all');
+    $this->assertText('To uninstall Forum, first delete all Forum content');
 
     // Delete the node.
     $this->drupalPostForm('node/' . $node->id() . '/delete', array(), t('Delete'));
@@ -83,7 +83,7 @@
     $this->drupalGet('admin/modules/uninstall');
     // Assert forum is still required.
     $this->assertNoFieldByName('uninstall[forum]');
-    $this->assertText('To uninstall Forum, first delete all');
+    $this->assertText('To uninstall Forum, first delete all Forums terms');
 
     // Delete any forum terms.
     $vid = $this->config('forum.settings')->get('vocabulary');
@@ -100,7 +100,6 @@
     $this->drupalGet('admin/modules/uninstall');
     // Assert forum is no longer required.
     $this->assertFieldByName('uninstall[forum]');
-    $this->assertNoText('To uninstall Forum first delete all Forum content');
     $this->drupalPostForm('admin/modules/uninstall', array(
       'uninstall[forum]' => 1,
     ), t('Uninstall'));
diff -u b/core/modules/forum/tests/src/Unit/ForumUninstallValidatorTest.php b/core/modules/forum/tests/src/Unit/ForumUninstallValidatorTest.php
--- b/core/modules/forum/tests/src/Unit/ForumUninstallValidatorTest.php
+++ b/core/modules/forum/tests/src/Unit/ForumUninstallValidatorTest.php
@@ -92,7 +92,7 @@
 
     $module = 'forum';
     $expected = [
-      'To uninstall Forum, first delete all <em>Forum</em> content.',
+      'To uninstall Forum, first delete all <em>Forum</em> content',
     ];
     $reasons = $this->forumUninstallValidator->validate($module);
     $this->assertSame($expected, $reasons);
@@ -126,8 +126,8 @@
 
     $module = 'forum';
     $expected = [
-      'To uninstall Forum, first delete all <em>Forum</em> content.',
-      SafeMarkup::format('To uninstall Forum, first delete all <a href="!url">%vocabulary</a> terms.', [
+      'To uninstall Forum, first delete all <em>Forum</em> content',
+      SafeMarkup::format('To uninstall Forum, first delete all <a href="!url">%vocabulary</a> terms', [
         '!url' => '/path/to/vocabulary/overview',
         '%vocabulary' => 'Vocabulary label',
       ]),
@@ -163,8 +163,8 @@
 
     $module = 'forum';
     $expected = [
-      'To uninstall Forum, first delete all <em>Forum</em> content.',
-      SafeMarkup::format('To uninstall Forum, first delete all %vocabulary terms.', [
+      'To uninstall Forum, first delete all <em>Forum</em> content',
+      SafeMarkup::format('To uninstall Forum, first delete all %vocabulary terms', [
         '%vocabulary' => 'Vocabulary label',
       ]),
     ];
@@ -200,7 +200,7 @@
 
     $module = 'forum';
     $expected = [
-      SafeMarkup::format('To uninstall Forum, first delete all <a href="!url">%vocabulary</a> terms.', [
+      SafeMarkup::format('To uninstall Forum, first delete all <a href="!url">%vocabulary</a> terms', [
         '!url' => '/path/to/vocabulary/overview',
         '%vocabulary' => 'Vocabulary label',
       ]),
@@ -236,7 +236,7 @@
 
     $module = 'forum';
     $expected = [
-      SafeMarkup::format('To uninstall Forum, first delete all %vocabulary terms.', [
+      SafeMarkup::format('To uninstall Forum, first delete all %vocabulary terms', [
         '%vocabulary' => 'Vocabulary label',
       ]),
     ];
diff -u b/core/modules/system/src/Tests/Module/DependencyTest.php b/core/modules/system/src/Tests/Module/DependencyTest.php
--- b/core/modules/system/src/Tests/Module/DependencyTest.php
+++ b/core/modules/system/src/Tests/Module/DependencyTest.php
@@ -168,7 +168,8 @@
 
     // Check that the comment module cannot be uninstalled.
     $this->drupalGet('admin/modules/uninstall');
-    $this->assertNoFieldByName('uninstall[checkbox]');
+    $checkbox = $this->xpath('//input[@type="checkbox" and @name="uninstall[comment]" and @disabled="disabled"]');
+    $this->assert(count($checkbox) == 1, 'Checkbox for uninstalling the comment module is disabled.');
 
     // Delete any forum terms.
     $vid = $this->config('forum.settings')->get('vocabulary');
diff -u b/core/modules/system/system.admin.inc b/core/modules/system/system.admin.inc
--- b/core/modules/system/system.admin.inc
+++ b/core/modules/system/system.admin.inc
@@ -310,9 +310,9 @@
     }
     if (!empty($form['modules'][$module]['#validation_reasons'])) {
       $disabled_message = \Drupal::translation()->formatPlural(count($form['modules'][$module]['#validation_reasons']),
-        'The following reason prevents @module from being uninstalled: !reasons',
-        'The following reasons prevents @module from being uninstalled: !reasons',
-        array('@module' => $form['modules'][$module]['#module_name'], '!reasons' => implode('; ', $form['modules'][$module]['#validation_reasons'])));
+        'The following reason prevents @module from being uninstalled: !reasons.',
+        'The following reasons prevents @module from being uninstalled: !reasons.',
+        array('@module' => $form['modules'][$module]['#module_name'], '!reasons' => SafeMarkup::checkAdminXss(implode('; ', $form['modules'][$module]['#validation_reasons']))));
     }
     $rows[] = array(
       array('data' => drupal_render($form['uninstall'][$module]), 'align' => 'center'),
diff -u b/core/modules/system/tests/modules/module_test/module_test.info.yml b/core/modules/system/tests/modules/module_required_test/module_required_test.info.yml
--- b/core/modules/system/tests/modules/module_test/module_test.info.yml
+++ b/core/modules/system/tests/modules/module_required_test/module_required_test.info.yml
@@ -1,6 +1,11 @@
-name: 'Module test'
+name: 'Module required test'
 type: module
 description: 'Support module for module system testing.'
 package: Testing
 version: VERSION
 core: 8.x
+# Depends on the Node module to test making a module required using
+# hook_system_info_alter() and ensuring that its dependencies also become
+# required.
+dependencies:
+  - drupal:node (>=8.x)
diff -u b/core/profiles/standard/src/Tests/StandardTest.php b/core/profiles/standard/src/Tests/StandardTest.php
--- b/core/profiles/standard/src/Tests/StandardTest.php
+++ b/core/profiles/standard/src/Tests/StandardTest.php
@@ -9,6 +9,7 @@
 
 use Drupal\config\Tests\SchemaCheckTestTrait;
 use Drupal\contact\Entity\ContactForm;
+use Drupal\filter\Entity\FilterFormat;
 use Drupal\simpletest\WebTestBase;
 use Drupal\user\Entity\Role;
 
@@ -117,6 +118,25 @@
       $this->assertConfigSchema($typed_config, $name, $config->get());
     }
 
+    // Ensure that configuration from the Standard profile is not reused when
+    // enabling a module again since it contains configuration that can not be
+    // installed. For example, editor.editor.basic_html is editor configuration
+    // that depends on the ckeditor module. The ckeditor module can not be
+    // installed before the editor module since it depends on the editor module.
+    // The installer does not have this limitation since it ensures that all of
+    // the install profiles dependencies are installed before creating the
+    // editor configuration.
+    foreach (FilterFormat::loadMultiple() as $filter) {
+      // Ensure that editor can be uninstalled by removing use in filter
+      // formats. It is necessary to prime the filter collection before removing
+      // the filter.
+      $filter->filters();
+      $filter->removeFilter('editor_file_reference');
+      $filter->save();
+    }
+    \Drupal::service('module_installer')->uninstall(array('editor', 'ckeditor'));
+    $this->rebuildContainer();
+    \Drupal::service('module_installer')->install(array('editor'));
     /** @var \Drupal\contact\ContactFormInterface $contact_form */
     $contact_form = ContactForm::load('feedback');
     $recipients = $contact_form->getRecipients();
diff -u b/core/tests/Drupal/Tests/Core/Extension/RequiredModuleUninstallValidatorTest.php b/core/tests/Drupal/Tests/Core/Extension/RequiredModuleUninstallValidatorTest.php
--- b/core/tests/Drupal/Tests/Core/Extension/RequiredModuleUninstallValidatorTest.php
+++ b/core/tests/Drupal/Tests/Core/Extension/RequiredModuleUninstallValidatorTest.php
@@ -72,7 +72,7 @@
       ->method('getModuleInfoByModule')
       ->willReturn(['required' => TRUE, 'name' => $module]);
 
-    $expected = [SafeMarkup::format('The @module module is required.', ['@module' => $module])];
+    $expected = [SafeMarkup::format('The @module module is required', ['@module' => $module])];
     $reasons = $this->uninstallValidator->validate($module);
     $this->assertSame($expected, $reasons);
   }
only in patch2:
unchanged:
--- a/core/lib/Drupal/Core/Extension/ModuleUninstallValidatorInterface.php
+++ b/core/lib/Drupal/Core/Extension/ModuleUninstallValidatorInterface.php
@@ -20,6 +20,10 @@
    *
    * @return string[]
    *   An array of reasons the module can not be uninstalled, empty if it can.
+   *   Each reason should not end with any punctuation since multiple reasons
+   *   can be displayed together.
+   *
+   * @see theme_system_modules_uninstall()
    */
   public function validate($module);
 }
only in patch2:
unchanged:
--- a/core/lib/Drupal/Core/Field/FieldModuleUninstallValidator.php
+++ b/core/lib/Drupal/Core/Field/FieldModuleUninstallValidator.php
@@ -53,7 +53,7 @@ public function validate($module_name) {
             if ($storage_definition->getProvider() == $module_name) {
               $storage = $this->entityManager->getStorage($entity_type_id);
               if ($storage instanceof FieldableEntityStorageInterface && $storage->countFieldData($storage_definition, TRUE)) {
-                $reasons[] = $this->t('There is data for the field @field-name on entity type @entity_type.', array(
+                $reasons[] = $this->t('There is data for the field @field-name on entity type @entity_type', array(
                   '@field-name' => $storage_definition->getName(),
                   '@entity_type' => $entity_type->getLabel(),
                 ));