diff --git a/lib/private/Files/Config/UserMountCache.php b/lib/private/Files/Config/UserMountCache.php
index bd8343fa440..6feb3085e9e 100644
--- a/lib/private/Files/Config/UserMountCache.php
+++ b/lib/private/Files/Config/UserMountCache.php
@@ -187,6 +187,9 @@ class UserMountCache implements IUserMountCache {
 
 	private function dbRowToMountInfo(array $row) {
 		$user = $this->userManager->get($row['user_id']);
+		if (is_null($user)) {
+			return null;
+		}
 		return new CachedMountInfo($user, (int)$row['storage_id'], (int)$row['root_id'], $row['mount_point'], $row['mount_id']);
 	}
 
@@ -203,7 +206,7 @@ class UserMountCache implements IUserMountCache {
 
 			$rows = $query->execute()->fetchAll();
 
-			$this->mountsForUsers[$user->getUID()] = array_map([$this, 'dbRowToMountInfo'], $rows);
+			$this->mountsForUsers[$user->getUID()] = array_filter(array_map([$this, 'dbRowToMountInfo'], $rows));
 		}
 		return $this->mountsForUsers[$user->getUID()];
 	}
@@ -220,7 +223,7 @@ class UserMountCache implements IUserMountCache {
 
 		$rows = $query->execute()->fetchAll();
 
-		return array_map([$this, 'dbRowToMountInfo'], $rows);
+		return array_filter(array_map([$this, 'dbRowToMountInfo'], $rows));
 	}
 
 	/**
@@ -235,7 +238,7 @@ class UserMountCache implements IUserMountCache {
 
 		$rows = $query->execute()->fetchAll();
 
-		return array_map([$this, 'dbRowToMountInfo'], $rows);
+		return array_filter(array_map([$this, 'dbRowToMountInfo'], $rows));
 	}
 
 	/**
diff --git a/tests/lib/Files/Config/UserMountCacheTest.php b/tests/lib/Files/Config/UserMountCacheTest.php
index 8e569c50e09..0fd9213e9a0 100644
--- a/tests/lib/Files/Config/UserMountCacheTest.php
+++ b/tests/lib/Files/Config/UserMountCacheTest.php
@@ -410,7 +410,7 @@ class UserMountCacheTest extends TestCase {
 	public function testGetMountsForFileIdDeletedUser() {
 		$user1 = $this->userManager->get('u1');
 
-		list($storage1, $rootId) = $this->getStorage(2);
+		$storage1 = $this->getStorage(1, 2);
 		$rootId = $this->createCacheEntry('', 2);
 		$mount1 = new MountPoint($storage1, '/foo/');
 		$this->cache->registerMounts($user1, [$mount1]);