MessageHTTPUploader.performUpload SocketException Socket is closed

Hello Team,

Our AS2 partner is getting below error while trying to transfer files from their Mendelson system to SAP BTP system.

MessageHTTPUploader.performUpload SocketException Socket is closed

As per SAP they can see it is due to missing intermediate CA from AS2 partner but they are saying all the certificate chain are available in their trust store.

Please anyone can help on this.

Regards,
Sunil Kumar T

Forum
AS2