Thread:Project:Support desk/Example of code to import xml into wiki using api import/reply

multipart/form-data content-type is a special way of sending content through HTTP.

By sending normal content and just setting a  header doesn't make your data to be automagically converted to multipart/form-data. Just like renaming a BMP file to have .jpg extension doesn't make it a JPG image.

I don't know what are you using for posting your data. You mention PHP. If you're using curl, the key may be using, using an array for  and not just appending text to it.