diff --git a/sitemap.module b/sitemap.module
index f181275..7ffa708 100644
--- a/sitemap.module
+++ b/sitemap.module
@@ -221,7 +221,7 @@ function _sitemap_menus($mid) {
  *   An integer representing a number of nodes. Results are statically cached.
  */
 function sitemap_taxonomy_term_count_nodes($tid) {
-  $query = db_select('taxonomy_index', 'ti');
+  $query = \Drupal::service('database')->select('taxonomy_index', 'ti');
   $query->addExpression('COUNT(ti.nid)');
   $count = $query
     ->condition('ti.tid', $tid)
diff --git a/sitemap.theme.inc b/sitemap.theme.inc
index 6b96134..cac1c6a 100644
--- a/sitemap.theme.inc
+++ b/sitemap.theme.inc
@@ -161,7 +161,7 @@ function template_preprocess_sitemap(array &$variables) {
         break;

       case 'vocabularies':
-        $vocabulary = \Drupal::entityManager()->getStorage('taxonomy_vocabulary')->load($id);
+        $vocabulary = \Drupal::entityTypeManager()->getStorage('taxonomy_vocabulary')->load($id);
         $vocabularies = $config->get('show_vocabularies');

         if ($vocabulary && !empty($vocabularies[$vocabulary->id()])) {
diff --git a/src/Form/SitemapSettingsForm.php b/src/Form/SitemapSettingsForm.php
index 1dff4aa..c768675 100644
--- a/src/Form/SitemapSettingsForm.php
+++ b/src/Form/SitemapSettingsForm.php
@@ -5,6 +5,7 @@ namespace Drupal\sitemap\Form;
 use Drupal\Core\Form\ConfigFormBase;
 use Drupal\Core\Config\ConfigFactory;
 use Drupal\Core\Extension\ModuleHandler;
+use Drupal\Core\Link;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\system\Entity\Menu;
@@ -86,7 +87,7 @@ class SitemapSettingsForm extends ConfigFormBase {
       '#type' => 'textfield',
       '#title' => $this->t('Page title'),
       '#default_value' => $config->get('page_title'),
-      '#description' => $this->t('Page title that will be used on the @sitemap_page.', ['@sitemap_page' => $this->l($this->t('sitemap page'), Url::fromRoute('sitemap.page'))]),
+      '#description' => $this->t('Page title that will be used on the @sitemap_page.', ['@sitemap_page' => Link::fromTextAndUrl($this->t('sitemap page'), Url::fromRoute('sitemap.page'))]),
     ];

     $sitemap_message = $config->get('message');
@@ -261,7 +262,7 @@ class SitemapSettingsForm extends ConfigFormBase {
       '#type' => 'checkbox',
       '#title' => $this->t('Include sitemap CSS file'),
       '#default_value' => $config->get('css'),
-      '#description' => $this->t("Select this box if you wish to load the CSS file included with the module. To learn how to override or specify the CSS at the theme level, visit the @documentation_page.", ['@documentation_page' => $this->l($this->t("documentation page"), Url::fromUri('https://www.drupal.org/node/2615568'))]),
+      '#description' => $this->t("Select this box if you wish to load the CSS file included with the module. To learn how to override or specify the CSS at the theme level, visit the @documentation_page.", ['@documentation_page' => Link::fromTextAndUrl($this->t("documentation page"), Url::fromUri('https://www.drupal.org/node/2615568'))]),
     ];

     if ($this->moduleHandler->moduleExists('book')) {
diff --git a/src/Tests/SitemapBookTest.php b/src/Tests/SitemapBookTest.php
index c6e08c3..e21b9e9 100644
--- a/src/Tests/SitemapBookTest.php
+++ b/src/Tests/SitemapBookTest.php
@@ -2,14 +2,14 @@

 namespace Drupal\sitemap\Tests;

-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;

 /**
  * Test the display of books based on sitemap settings.
  *
  * @group sitemap
  */
-class SitemapBookTest extends WebTestBase {
+class SitemapBookTest extends BrowserTestBase {

   /**
    * Modules to enable.
diff --git a/src/Tests/SitemapContentTest.php b/src/Tests/SitemapContentTest.php
index 751b818..d1563b2 100644
--- a/src/Tests/SitemapContentTest.php
+++ b/src/Tests/SitemapContentTest.php
@@ -2,7 +2,7 @@

 namespace Drupal\sitemap\Tests;

-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;
 use Drupal\filter\Entity\FilterFormat;

 /**
@@ -10,7 +10,7 @@ use Drupal\filter\Entity\FilterFormat;
  *
  * @group sitemap
  */
-class SitemapContentTest extends WebTestBase {
+class SitemapContentTest extends BrowserTestBase {

   /**
    * Modules to enable.
diff --git a/src/Tests/SitemapCssTest.php b/src/Tests/SitemapCssTest.php
index 197d75f..f31d982 100644
--- a/src/Tests/SitemapCssTest.php
+++ b/src/Tests/SitemapCssTest.php
@@ -2,14 +2,14 @@

 namespace Drupal\sitemap\Tests;

-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;

 /**
  * Tests the inclusion of the sitemap css file based on sitemap settings.
  *
  * @group sitemap
  */
-class SitemapCssTest extends WebTestBase {
+class SitemapCssTest extends BrowserTestBase {

   /**
    * Modules to enable.
diff --git a/src/Tests/SitemapMenuTestBase.php b/src/Tests/SitemapMenuTestBase.php
index 93734b3..d119b77 100644
--- a/src/Tests/SitemapMenuTestBase.php
+++ b/src/Tests/SitemapMenuTestBase.php
@@ -2,12 +2,12 @@

 namespace Drupal\sitemap\Tests;

-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;

 /**
  * Test the display of menus based on sitemap settings.
  */
-abstract class SitemapMenuTestBase extends WebTestBase {
+abstract class SitemapMenuTestBase extends BrowserTestBase {

   /**
    * Modules to enable.
diff --git a/src/Tests/SitemapRssTest.php b/src/Tests/SitemapRssTest.php
index a1b2fe0..e7d1a1a 100644
--- a/src/Tests/SitemapRssTest.php
+++ b/src/Tests/SitemapRssTest.php
@@ -2,15 +2,14 @@

 namespace Drupal\sitemap\Tests;

-use Drupal\Component\Utility\Unicode;
-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;

 /**
  * Tests the display of RSS links based on sitemap settings.
  *
  * @group sitemap
  */
-class SitemapRssTest extends WebTestBase {
+class SitemapRssTest extends BrowserTestBase {

   /**
    * Modules to enable.
@@ -42,7 +41,7 @@ class SitemapRssTest extends WebTestBase {
     $this->assertLinkByHref('/rss.xml');

     // Change RSS feed for front page.
-    $href = Unicode::strtolower($this->randomMachineName());
+    $href = mb_strtolower($this->randomMachineName());
     $edit = [
       'rss_front' => $href,
     ];
diff --git a/src/Tests/SitemapTaxonomyTestBase.php b/src/Tests/SitemapTaxonomyTestBase.php
index 20cb9d4..7dc7225 100644
--- a/src/Tests/SitemapTaxonomyTestBase.php
+++ b/src/Tests/SitemapTaxonomyTestBase.php
@@ -2,10 +2,10 @@

 namespace Drupal\sitemap\Tests;

-use Drupal\taxonomy\Tests\TaxonomyTestBase;
 use Drupal\Core\Entity\Entity\EntityFormDisplay;
 use Drupal\Core\Field\FieldStorageDefinitionInterface;
 use Drupal\taxonomy\Entity\Vocabulary;
+use Drupal\Tests\taxonomy\Functional\TaxonomyTestBase;

 /**
  * Base class for some Sitemap test cases.
diff --git a/src/Form/SitemapSettingsForm.php b/sitemap/src/Form/SitemapSettingsForm.php
--- a/src/Form/SitemapSettingsForm.php	(date 1628685718029)
+++ b/src/Form/SitemapSettingsForm.php	(date 1628685718029)
@@ -87,7 +87,9 @@
       '#type' => 'textfield',
       '#title' => $this->t('Page title'),
       '#default_value' => $config->get('page_title'),
-      '#description' => $this->t('Page title that will be used on the @sitemap_page.', ['@sitemap_page' => Link::fromTextAndUrl($this->t('sitemap page'), Url::fromRoute('sitemap.page'))]),
+      '#description' => $this->t('Page title that will be used on the <a href="@sitemap_page_url">sitemap page</a>.', [
+        '@sitemap_page_url' => Url::fromRoute('sitemap.page')->toString(),
+      ]),
     ];

     $sitemap_message = $config->get('message');
diff --git a/src/Form/SitemapSettingsForm.php b/sitemap/src/Form/SitemapSettingsForm.php
--- a/src/Form/SitemapSettingsForm.php	(date 1628686015873)
+++ b/src/Form/SitemapSettingsForm.php	(date 1628686015873)
@@ -264,7 +264,7 @@
       '#type' => 'checkbox',
       '#title' => $this->t('Include sitemap CSS file'),
       '#default_value' => $config->get('css'),
-      '#description' => $this->t("Select this box if you wish to load the CSS file included with the module. To learn how to override or specify the CSS at the theme level, visit the @documentation_page.", ['@documentation_page' => Link::fromTextAndUrl($this->t("documentation page"), Url::fromUri('https://www.drupal.org/node/2615568'))]),
+      '#description' => $this->t('Select this box if you wish to load the CSS file included with the module. To learn how to override or specify the CSS at the theme level, visit the <a href="https://www.drupal.org/node/2615568">documentation page</a>.'),
     ];

     if ($this->moduleHandler->moduleExists('book')) {