diff --git a/lib/Listener/TaskProcessingListener.php b/lib/Listener/TaskProcessingListener.php
index fa55217378..dc93b180ff 100644
--- a/lib/Listener/TaskProcessingListener.php
+++ b/lib/Listener/TaskProcessingListener.php
@@ -60,8 +60,14 @@ public function handle(Event $event): void {
 			$this->logger->info('Error handling task processing event user id missing');
 			return;
 		}
-		if ($task->getOutput() !== null && isset($task->getOutput()['output'])) {
-			$summary = (string)$task->getOutput()['output'];
+		if ($task->getOutput() !== null) {
+			$output = $task->getOutput();
+			if (isset($task->getOutput()['output'])) {
+				$summary = (string)$output['output'];
+			} else {
+				$this->logger->info('Error handling task processing event output is invalid');
+				return;
+			}
 		} else {
 			$this->logger->info('Error handling task processing event output missing');
 			return;