diff --git a/lib/Controller/OcsApiController.php b/lib/Controller/OcsApiController.php
index 2ab4f1ac..3f61185d 100644
--- a/lib/Controller/OcsApiController.php
+++ b/lib/Controller/OcsApiController.php
@@ -49,6 +49,9 @@ public function createUser(
 	): DataResponse {
 		$backendUser = $this->userMapper->getOrCreate($providerId, $userId);
 		$user = $this->userManager->get($backendUser->getUserId());
+		if ($user === null) {
+			throw new \RuntimeException('Unable to get user that was just created with userId=' . $backendUser->getUserId());
+		}
 
 		if ($displayName) {
 			if ($displayName !== $backendUser->getDisplayName()) {
diff --git a/lib/Db/User.php b/lib/Db/User.php
index 03126e00..f7b6f6c9 100644
--- a/lib/Db/User.php
+++ b/lib/Db/User.php
@@ -27,5 +27,6 @@ class User extends Entity {
 
 	public function __construct() {
 		$this->addType('userId', Types::STRING);
+		$this->addType('displayName', Types::STRING);
 	}
 }
diff --git a/lib/Db/UserMapper.php b/lib/Db/UserMapper.php
index 2f91604c..b2083c33 100644
--- a/lib/Db/UserMapper.php
+++ b/lib/Db/UserMapper.php
@@ -167,7 +167,10 @@ public function getOrCreate(int $providerId, string $sub, bool $id4me = false):
 
 		$user = new User();
 		$user->setUserId($userId);
-		return $this->insert($user);
+		$user->setDisplayName('');
+		$user = $this->insert($user);
+		$this->userCache->set($userId, $user);
+		return $user;
 	}
 
 	/**