NAV 2018. How to export XML file

Hi!

I am new here and also still learning NAV 2018, so my knowledge is limited.

I have an issue: when I go to Sales Order and select a specific customer, then try to Post -> Invoice -> Ok, I get an error.

I don’t understand why, but I heard that it’s possible to export an XML file to see what the problem is.

Could you please advise how to do this or suggest other ways to solve the issue?

Thank you and have a great day!