diff --git a/lib/Controller/MentionController.php b/lib/Controller/MentionController.php
index 3e5496ef4d..441af7d15f 100644
--- a/lib/Controller/MentionController.php
+++ b/lib/Controller/MentionController.php
@@ -38,7 +38,7 @@ public function mention(int $fileId, string $mention): DataResponse {
 		$userFolder = $this->rootFolder->getUserFolder($this->userId);
 		$file = $userFolder->getFirstNodeById($fileId);
 		if ($file === null) {
-			return new DataResponse([], Http::STATUS_NOT_FOUND);
+			return new DataResponse(['message' => 'File not found for current user'], Http::STATUS_NOT_FOUND);
 		}
 
 		// Reverse the array of users to pop off the first user later
@@ -52,7 +52,7 @@ public function mention(int $fileId, string $mention): DataResponse {
 		$userFolder = $this->rootFolder->getUserFolder($user->getUID());
 		$file = $userFolder->getFirstNodeById($fileId);
 		if ($file === null) {
-			return new DataResponse([], Http::STATUS_NOT_FOUND);
+			return new DataResponse(['message' => 'File not found for mentioned user'], Http::STATUS_NOT_FOUND);
 		}
 
 		$notification = $this->manager->createNotification();
@@ -70,6 +70,6 @@ public function mention(int $fileId, string $mention): DataResponse {
 			return new DataResponse([], Http::STATUS_OK);
 		}
 
-		return new DataResponse([], Http::STATUS_NOT_FOUND);
+		return new DataResponse(['message' => 'Notification already present'], Http::STATUS_NOT_FOUND);
 	}
 }