diff --git a/lib/Controller/ThreadController.php b/lib/Controller/ThreadController.php
index fd06e20168..aa45c4e3ef 100755
--- a/lib/Controller/ThreadController.php
+++ b/lib/Controller/ThreadController.php
@@ -125,7 +125,7 @@ public function delete(int $id): JSONResponse {
 	/**
 	 * @NoAdminRequired
 	 *
-	 * @param int $id
+	 * @param string $id
 	 * @param int $accountId
 	 *
 	 * @return JSONResponse
@@ -134,7 +134,7 @@ public function summarize(string $id, int $accountId): JSONResponse {
 		try {
 			$account = $this->accountService->find($this->currentUserId, $accountId);
 			$messages = $this->mailManager->getThread($account, $id);
-		} catch (DoesNotExistException $e) {
+		} catch (ClientException $e) {
 			return new JSONResponse([], Http::STATUS_FORBIDDEN);
 		}
 
@@ -151,7 +151,7 @@ public function summarize(string $id, int $accountId): JSONResponse {
 			return new JSONResponse([], Http::STATUS_NO_CONTENT);
 		}
 
-		return new JSONResponse($summary);
+		return new JSONResponse([$summary]);
 	}
 
 }