diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 7bca0ad9..da07d8a4 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,10 +1,11 @@
+# To add new Drupal versions, update quant-ci-images repo.
 name: Test and code coverage
 on:
   - push
 jobs:
   lint:
     runs-on: ubuntu-latest
-    container: quantcdn/drupal-ci:9.4.x-dev
+    container: quantcdn/drupal-ci:11.0.x-dev
     steps:
       - uses: actions/checkout@v2
       - name: Lint
@@ -12,7 +13,7 @@ jobs:
 
   phpunit:
     runs-on: ubuntu-latest
-    container: quantcdn/drupal-ci:9.4.x-dev
+    container: quantcdn/drupal-ci:11.0.x-dev
 
     services:
       mariadb:
@@ -20,7 +21,7 @@ jobs:
         ports:
           - 3306:3306
         env:
-          MYSQL_DATABASE: drupal9
+          MYSQL_DATABASE: drupal
           MYSQL_ROOT_PASSWORD: drupal
           MYSQL_USER: drupal
           MYSQL_PASSWORD: drupal
@@ -32,7 +33,7 @@ jobs:
 
     steps:
       - name: Install Drupal
-        run: drush si --db-url=mysql://root:drupal@mariadb:3306/drupal9 -y
+        run: drush si --db-url=mysql://root:drupal@mariadb:3306/drupal -y
         working-directory: /var/www/drupal
 
       - name: Install module dependencies
diff --git a/modules/quant_api/src/Client/QuantClient.php b/modules/quant_api/src/Client/QuantClient.php
index 1f03c168..534ad18a 100644
--- a/modules/quant_api/src/Client/QuantClient.php
+++ b/modules/quant_api/src/Client/QuantClient.php
@@ -270,7 +270,7 @@ public function sendRedirect(array $data) : array {
   /**
    * {@inheritdoc}
    */
-  public function sendFile(string $file, string $url, int $rid = NULL) : array {
+  public function sendFile(string $file, string $url, ?int $rid = NULL) : array {
 
     // Ensure the file is accessible before attempting to send to the API.
     if (!file_exists($file) || !is_readable($file) || !is_file($file)) {
diff --git a/modules/quant_api/src/Client/QuantClientInterface.php b/modules/quant_api/src/Client/QuantClientInterface.php
index cc7a40fc..7266618b 100644
--- a/modules/quant_api/src/Client/QuantClientInterface.php
+++ b/modules/quant_api/src/Client/QuantClientInterface.php
@@ -65,7 +65,7 @@ public function send(array $data) : array;
    * @throws \Drupal\quant_api\Exception\InvalidPayload
    * @throws \Drupal\quant_api\Exception\InvalidResposne
    */
-  public function sendFile(string $file, string $url, int $rid = NULL) : array;
+  public function sendFile(string $file, string $url, ?int $rid = NULL) : array;
 
   /**
    * Send a redirect to the API.
diff --git a/modules/quant_api/tests/src/Unit/QuantClientTest.php b/modules/quant_api/tests/src/Unit/QuantClientTest.php
index 31dd205a..184d50fb 100644
--- a/modules/quant_api/tests/src/Unit/QuantClientTest.php
+++ b/modules/quant_api/tests/src/Unit/QuantClientTest.php
@@ -2,12 +2,13 @@
 
 namespace Drupal\Tests\quant_api\Unit;
 
-use Drupal\Tests\UnitTestCase;
-use Drupal\quant_api\Client\QuantClient;
-use GuzzleHttp\Client;
 use Drupal\Core\Logger\LoggerChannelFactoryInterface;
 use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Config\ImmutableConfig;
+use Drupal\quant_api\Client\QuantClient;
+use Drupal\quant_api\Exception\InvalidPayload;
+use Drupal\Tests\UnitTestCase;
+use GuzzleHttp\Client;
 use GuzzleHttp\Exception\RequestException;
 use GuzzleHttp\Psr7\Response;
 use GuzzleHttp\RequestOptions;
@@ -201,7 +202,7 @@ public function testSendValid() {
    * Ensure that send handles server errors.
    */
   public function testSendError() {
-    $this->expectException(\GuzzleHttp\Exception\RequestException::class);
+    $this->expectException(RequestException::class);
     $http = $this->prophesize(Client::class);
     $logger = $this->prophesize(LoggerChannelFactoryInterface::class);
     $config = $this->getConfigStub();
@@ -255,7 +256,7 @@ public function testSendRedirectValid() {
    * Ensure a valid redirect response is sent.
    */
   public function testSendRedirectError() {
-    $this->expectException(\GuzzleHttp\Exception\RequestException::class);
+    $this->expectException(RequestException::class);
     $http = $this->prophesize(Client::class);
     $logger = $this->prophesize(LoggerChannelFactoryInterface::class);
     $config = $this->getConfigStub();
@@ -278,7 +279,7 @@ public function testSendRedirectError() {
    * Ensure files are validated before sending.
    */
   public function testSendFileFileNoExist() {
-    $this->expectException(\Drupal\quant_api\Exception\InvalidPayload::class);
+    $this->expectException(InvalidPayload::class);
     // phpcs:ignore
     global $exists_return;
     // phpcs:ignore
diff --git a/modules/quant_search/src/Form/ConfirmIndexClearForm.php b/modules/quant_search/src/Form/ConfirmIndexClearForm.php
index 43c32954..e97a16e1 100644
--- a/modules/quant_search/src/Form/ConfirmIndexClearForm.php
+++ b/modules/quant_search/src/Form/ConfirmIndexClearForm.php
@@ -14,7 +14,7 @@ class ConfirmIndexClearForm extends ConfirmFormBase {
   /**
    * {@inheritdoc}
    */
-  public function buildForm(array $form, FormStateInterface $form_state, string $id = NULL) {
+  public function buildForm(array $form, FormStateInterface $form_state, ?string $id = NULL) {
     return parent::buildForm($form, $form_state);
   }
 
diff --git a/src/Controller/QuantNodeViewController.php b/src/Controller/QuantNodeViewController.php
index 7ab518b2..871ca147 100644
--- a/src/Controller/QuantNodeViewController.php
+++ b/src/Controller/QuantNodeViewController.php
@@ -53,7 +53,7 @@ class QuantNodeViewController extends NodeViewController {
    * @param \Drupal\Core\Session\AccountSwitcherInterface $account_switcher
    *   The account switcher interface.
    */
-  public function __construct(EntityTypeManagerInterface $entity_type_manager, RendererInterface $renderer, AccountInterface $current_user = NULL, EntityRepositoryInterface $entity_repository = NULL, RequestStack $request_stack, CurrentRouteMatch $route_match, AccountSwitcherInterface $account_switcher) {
+  public function __construct(EntityTypeManagerInterface $entity_type_manager, RendererInterface $renderer, ?AccountInterface $current_user = NULL, ?EntityRepositoryInterface $entity_repository = NULL, RequestStack $request_stack, CurrentRouteMatch $route_match, AccountSwitcherInterface $account_switcher) {
     parent::__construct($entity_type_manager, $renderer, $current_user, $entity_repository);
 
     $this->accountSwitcher = $account_switcher;
diff --git a/src/Event/ConfigFormEventBase.php b/src/Event/ConfigFormEventBase.php
index 43a06fa2..a8fa651c 100644
--- a/src/Event/ConfigFormEventBase.php
+++ b/src/Event/ConfigFormEventBase.php
@@ -36,7 +36,7 @@ class ConfigFormEventBase extends Event implements ConfigFormEventInterface {
   /**
    * {@inheritdoc}
    */
-  public function __construct(FormStateInterface $form_state = NULL) {
+  public function __construct(?FormStateInterface $form_state = NULL) {
     $this->formState = $form_state;
   }
 
diff --git a/src/Event/ConfigFormEventInterface.php b/src/Event/ConfigFormEventInterface.php
index 7bdc3640..1cdea35e 100644
--- a/src/Event/ConfigFormEventInterface.php
+++ b/src/Event/ConfigFormEventInterface.php
@@ -15,7 +15,7 @@ interface ConfigFormEventInterface {
    * @param Drupal\Core\Form\FormStateInterface $form_state
    *   The configuration values.
    */
-  public function __construct(FormStateInterface $form_state = NULL);
+  public function __construct(?FormStateInterface $form_state = NULL);
 
   /**
    * Accessor for the form state.
diff --git a/src/Exception/ExpiredTokenException.php b/src/Exception/ExpiredTokenException.php
index 8fd3e46b..3780c286 100644
--- a/src/Exception/ExpiredTokenException.php
+++ b/src/Exception/ExpiredTokenException.php
@@ -31,7 +31,7 @@ class ExpiredTokenException extends \Exception {
   /**
    * {@inheritdoc}
    */
-  public function __construct(string $token, int $time = 0, $sTime = 0, string $message = "The token has expired", int $code = 0, \Throwable $previous = NULL) {
+  public function __construct(string $token, int $time = 0, $sTime = 0, string $message = "The token has expired", int $code = 0, ?\Throwable $previous = NULL) {
     $this->token = $token;
     $this->time = $time;
     $this->sTime = $sTime;
diff --git a/src/Exception/InvalidTokenException.php b/src/Exception/InvalidTokenException.php
index 4591f82d..19a5df5e 100644
--- a/src/Exception/InvalidTokenException.php
+++ b/src/Exception/InvalidTokenException.php
@@ -24,7 +24,7 @@ class InvalidTokenException extends \Exception {
   /**
    * {@inheritdoc}
    */
-  public function __construct(string $token, int $time = 0, string $message = "Invalid request token", int $code = 0, \Throwable $previous = NULL) {
+  public function __construct(string $token, int $time = 0, string $message = "Invalid request token", int $code = 0, ?\Throwable $previous = NULL) {
     $this->token = $token;
     $this->time = $time;
 
diff --git a/src/Exception/StrictTokenException.php b/src/Exception/StrictTokenException.php
index e6352187..39e9d8c9 100644
--- a/src/Exception/StrictTokenException.php
+++ b/src/Exception/StrictTokenException.php
@@ -31,7 +31,7 @@ class StrictTokenException extends \Exception {
   /**
    * {@inheritdoc}
    */
-  public function __construct(string $token, $token_route = NULL, $expected_route = NULL, string $message = "The token routes do not match", int $code = 0, \Throwable $previous = NULL) {
+  public function __construct(string $token, $token_route = NULL, $expected_route = NULL, string $message = "The token routes do not match", int $code = 0, ?\Throwable $previous = NULL) {
     $this->token = $token;
     $this->tokenRoute = $token_route;
     $this->expectedRoute = $expected_route;
diff --git a/src/Utility.php b/src/Utility.php
index 44efaf51..ed57fa8b 100644
--- a/src/Utility.php
+++ b/src/Utility.php
@@ -45,7 +45,7 @@ public static function usesLanguagePathPrefixes() : bool {
    * @return string
    *   The URL adjusted for multilingual settings. Defaults to current url.
    */
-  public static function getUrl(string $url = NULL, string $langcode = NULL) : string {
+  public static function getUrl(?string $url = NULL, ?string $langcode = NULL) : string {
 
     // Default to current URL.
     if (!$url) {
@@ -77,7 +77,7 @@ public static function getUrl(string $url = NULL, string $langcode = NULL) : str
    * @return string
    *   The path prefix based on multilingual settings. Defaults to '/'.
    */
-  public static function getPathPrefix(string $langcode = NULL) : string {
+  public static function getPathPrefix(?string $langcode = NULL) : string {
 
     // Always start with a slash.
     $prefix = '/';
@@ -200,7 +200,7 @@ public static function getSpecialPages() {
    * @return string
    *   The markup with the page info.
    */
-  public static function getPageInfo(array $urls = NULL) : string {
+  public static function getPageInfo(?array $urls = NULL) : string {
     try {
       // Only allow administrators and content editors access.
       $roles = ['administrator', 'content_editor', 'editor'];