GSTR1 - Unable to upload JSON file on GST Portal.

Hi,

While uploading the JSON file on GST portal following error is shown

"File could not be uploaded! Download the latest version of Offline tool to generate the JSON file or ensure to validate your uploaded file against the template published at Specification Portal." 

I am using the latest offline tool version V2.3.1. Have also mailed to helpdesk, no response as yet.

Can anyone help resolve the issue.