diff --git a/apps/provisioning_api/lib/AppInfo/Application.php b/apps/provisioning_api/lib/AppInfo/Application.php
index 6d99c48be5..c706cd38a1 100644
--- a/apps/provisioning_api/lib/AppInfo/Application.php
+++ b/apps/provisioning_api/lib/AppInfo/Application.php
@@ -29,11 +29,14 @@ namespace OCA\Provisioning_API\AppInfo;
 
 use OC\AppFramework\Utility\SimpleContainer;
 use OC\AppFramework\Utility\TimeFactory;
+use OC\Group\Manager as GroupManager;
 use OCA\Provisioning_API\Middleware\ProvisioningApiMiddleware;
 use OCA\Settings\Mailer\NewUserMailHelper;
 use OCP\AppFramework\App;
 use OCP\AppFramework\Utility\IControllerMethodReflector;
 use OCP\Defaults;
+use OCP\IGroupManager;
+use OCP\IUser;
 use OCP\Util;
 
 class Application extends App {
@@ -58,8 +61,16 @@ class Application extends App {
 		});
 		$container->registerService('ProvisioningApiMiddleware', function (SimpleContainer $c) use ($server) {
 			$user = $server->getUserManager()->get($c['UserId']);
-			$isAdmin = $user !== null ? $server->getGroupManager()->isAdmin($user->getUID()) : false;
-			$isSubAdmin = $user !== null ? $server->getGroupManager()->getSubAdmin()->isSubAdmin($user) : false;
+			$isAdmin = false;
+			$isSubAdmin = false;
+
+			if ($user instanceof IUser) {
+				$groupManager = $server->get(IGroupManager::class);
+				assert($groupManager instanceof GroupManager);
+				$isAdmin = $groupManager->isAdmin($user->getUID());
+				$isSubAdmin = $groupManager->getSubAdmin()->isSubAdmin($user);
+			}
+
 			return new ProvisioningApiMiddleware(
 				$c->query(IControllerMethodReflector::class),
 				$isAdmin,