Validation Error for SAFT-PT Version 1.03_01

Hi Experts,

I'm facing an issues as my java validator is throwing below error while submitting the Tax audit XML file on Portugal tax audit website.

Validator version = BEM-VINDO AO VALIDADOR DE FICHEIROS SAF-T(PT) VERSÃO 1.03_01

Error message = Content is not allowed in prolog

Error screen shot = capture.png

XML size is = 900 MB

SAP version = 2.46

Java Version = JDK 8

Can you please suggest how do I resolve it?

BR/Sandy