Importing a xml with external DTD (NAV 2015)

Hi all,

I am trying to import an xml file with an external DTD into NAV 2015. We are migrating from 4.03, in this version it was runnig well.

Now I am getting:

For security reasons DTD is prohibited in this XML document. To enable DTD processing set the DtdProcessing property on XmlReaderSettings to Parse and pass the settings into XmlReader.Create method.

The XML file is starting like this

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE ORDER SYSTEM "http://www.............(valid path)..................dtd">
<ORDER type="standard" version="1.0">

I cant find out how to solve it, what am I doing wrong?

Regards