diff --git a/lib/private/Log/File.php b/lib/private/Log/File.php
index 597cb54e402..c881c6dd9de 100644
--- a/lib/private/Log/File.php
+++ b/lib/private/Log/File.php
@@ -145,6 +145,9 @@ class File implements IWriter, IFileBased {
 			error_log($entry);
 		}
 		if (php_sapi_name() === 'cli-server') {
+			if (!\is_string($message)) {
+				$message = json_encode($message);
+			}
 			error_log($message, 4);
 		}
 	}