diff --git a/lib/private/User/LazyUser.php b/lib/private/User/LazyUser.php
index cd3e268be48bc..92a0c73521514 100644
--- a/lib/private/User/LazyUser.php
+++ b/lib/private/User/LazyUser.php
@@ -36,9 +36,12 @@ private function getUser(): IUser {
 				$this->user = $this->userManager->get($this->uid);
 			}
 		}
-		/** @var IUser */
-		$user = $this->user;
-		return $user;
+
+		if ($this->user === null) {
+			throw new NoUserException('User not found in backend');
+		}
+
+		return $this->user;
 	}
 
 	public function getUID() {
diff --git a/lib/private/User/Manager.php b/lib/private/User/Manager.php
index e21759b1e9865..773f806750c23 100644
--- a/lib/private/User/Manager.php
+++ b/lib/private/User/Manager.php
@@ -60,14 +60,13 @@ class Manager extends PublicEmitter implements IUserManager {
 	 */
 	private array $cachedUsers = [];
 
-	private ICache $cache;
-
 	private DisplayNameCache $displayNameCache;
 
 	public function __construct(
 		private IConfig $config,
 		ICacheFactory $cacheFactory,
 		private IEventDispatcher $eventDispatcher,
+		private LoggerInterface $logger,
 	) {
 		$this->cache = new WithLocalCache($cacheFactory->createDistributed('user_backend_map'));
 		$this->listen('\OC\User', 'postDelete', function (IUser $user): void {
@@ -201,7 +200,7 @@ public function checkPassword($loginName, $password) {
 		$result = $this->checkPasswordNoLogging($loginName, $password);
 
 		if ($result === false) {
-			\OCP\Server::get(LoggerInterface::class)->warning('Login failed: \'' . $loginName . '\' (Remote IP: \'' . \OC::$server->getRequest()->getRemoteAddress() . '\')', ['app' => 'core']);
+			$this->logger->warning('Login failed: \'' . $loginName . '\' (Remote IP: \'' . \OC::$server->getRequest()->getRemoteAddress() . '\')', ['app' => 'core']);
 		}
 
 		return $result;
@@ -319,11 +318,16 @@ public function getDisabledUsers(?int $limit = null, int $offset = 0, string $se
 		if ($search !== '') {
 			$users = array_filter(
 				$users,
-				fn (IUser $user): bool =>
-					mb_stripos($user->getUID(), $search) !== false ||
-					mb_stripos($user->getDisplayName(), $search) !== false ||
-					mb_stripos($user->getEMailAddress() ?? '', $search) !== false,
-			);
+				function (IUser $user) use ($search): bool {
+					try {
+						return mb_stripos($user->getUID(), $search) !== false ||
+						mb_stripos($user->getDisplayName(), $search) !== false ||
+						mb_stripos($user->getEMailAddress() ?? '', $search) !== false;
+					} catch (NoUserException $ex) {
+						$this->logger->error('Error while filtering disabled users', ['exception' => $ex, 'userUID' => $user->getUID()]);
+						return false;
+					}
+			});
 		}
 
 		$tempLimit = ($limit === null ? null : $limit + $offset);