Safari 11.1: ajax/XHR form submission fails when input[type=file] is empty

Question

UPDATE: As of Webkit build r230963, this issue has been resolved in Webkit.

===========

Since the recent Safari 11.1 update on macOS and iOS, as

Answer 1

I worked on what appears to be the same issue in a Perl-program

Processing multipart/form-data in Perl invokes Apache-error with Apple-devices, when a form-file-element is empty

Workaround is removing the form-elements before the formdata is assigned:

$('#myForm').find("input[type='file']").each(function(){
    if ($(this).get(0).files.length === 0) {$(this).remove();}
});
var fData = new FormData($('#myForm')[0]);
...