Michael Lutz
--- a/src/Controller/SimplesamlphpAuthController.php
+++ b/src/Controller/SimplesamlphpAuthController.php
   *   A logger instance.
   * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
   *   The configuration factory.
+   * @param \Drupal\Core\PageCache\ResponsePolicy\KillSwitch $page_cache_kill_switch
+   *   The page cache kill switch.
   */
-  public function __construct(SimplesamlphpAuthManager $simplesaml, SimplesamlphpDrupalAuth $simplesaml_drupalauth, UrlGeneratorInterface $url_generator, RequestStack $request_stack, AccountInterface $account, PathValidatorInterface $path_validator, LoggerInterface $logger, ConfigFactoryInterface $config_factory) {
--- a/src/EventSubscriber/SimplesamlSubscriber.php
+++ b/src/EventSubscriber/SimplesamlSubscriber.php
+   *   simplesamlphp_auth:5.0.0. Use loginDirectlyWithExternalIdP instead.
+   * @see https://www.drupal.org/project/simplesamlphp_auth/issues/3401289
   */
+  // @codingStandardsIgnoreLine
  public function login_directly_with_external_IdP(RequestEvent $event) {
+    @trigger_error(__METHOD__ . '() is deprecated in simplesamplphp_auth:4.1.0 and is removed from simplesamlphp_auth:5.0.0. Use loginDirectlyWithExternalIdP instead. See https://www.drupal.org/project/simplesamlphp_auth/issues/3401289', E_USER_DEPRECATED);
+    $this->loginDirectlyWithExternalIdP($event);
+  }
+
+  /**
+   * Redirect anonymous users to the external IdP from the Drupal login page.
+   *
+   * @param \Symfony\Component\HttpKernel\Event\RequestEvent $event
+   *   The subscribed event.
+   */
+  public function loginDirectlyWithExternalIdP(RequestEvent $event) {
--- a/src/Service/SimplesamlphpDrupalAuth.php
+++ b/src/Service/SimplesamlphpDrupalAuth.php
        $account = $this->externalauth->register($authname, 'simplesamlphp_auth');
      }
      catch (\Exception $ex) {
-        watchdog_exception('simplesamlphp_auth', $ex);
+        // @todo remove when Drupal 10.0 is no longer supported.
--- a/tests/src/Unit/Service/SimplesamlphpDrupalAuthTest.php
+++ b/tests/src/Unit/Service/SimplesamlphpDrupalAuthTest.php
      ->will($this->returnValue($attributes));

    // Set up a mock for SimplesamlphpDrupalAuth class,
-    // mocking getUserIdforAuthname() and externalRegister() methods.
+    // mocking externalRegister() method.
    $simplesaml_drupalauth = $this->getMockBuilder('Drupal\simplesamlphp_auth\Service\SimplesamlphpDrupalAuth')
-      ->setMethods(['externalLoginFinalize'])
--- a/src/Controller/SimplesamlphpAuthController.php
+++ b/src/Controller/SimplesamlphpAuthController.php
 use Drupal\Core\Path\PathValidatorInterface;
 use Drupal\Core\Routing\UrlGeneratorInterface;
 use Drupal\Core\Session\AccountInterface;
 use Drupal\simplesamlphp_auth\Service\SimplesamlphpAuthManager;
 use Drupal\simplesamlphp_auth\Service\SimplesamlphpDrupalAuth;
 use Psr\Log\LoggerInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\HttpFoundation\RedirectResponse;
 use Symfony\Component\HttpFoundation\RequestStack;
-use Symfony\Component\DependencyInjection\ContainerInterface;
-use Drupal\Core\Config\ConfigFactoryInterface;

 /**
 * Controller routines for simplesamlphp_auth routes.
+ *
+ * @phpstan-consistent-constructor