Unable to import zip with all assets - Bad Gateway

Problem/Motivation

Unable to import zip file exported of a content type having good number of components within it

An AJAX HTTP error occurred.
HTTP Result Code: 502
Debugging information follows.
Path: /batch?id=6746686&op=do_nojs&op=do
StatusText: error
ResponseText:
502 Bad Gateway
502 Bad Gateway
nginx

My observation is that the function validateYamlFileContent() is causing Bad Gateway when trying to decode the YML file

$content = Yaml::decode($content); in /single_content_sync/src/ContentSyncHelper.php

If anybody has faced similar issue, please advise