How to import blog posts from WordPress 3.6 into WordPress 3.8.1?

I have exported all blog posts from a wordpress 3.6 install. The XML file is 1.63MB.

I have activated the wordpress importer on a new wordpress 3.8.1 install and have attempted to import the XML file. The result is a blank screen, without any errors.

This thread says I may be having problems as the XML format may vary between versions.

Anyone had any luck with this process?