@joncave
I’m also getting
Sorry, there has been an error.
This does not appear to be a WXR file, missing/invalid WXR version number
when trying to import into an upgraded 3.3.1 wordpress install.
I can confirm my WP XML Export contains
<language>en</language>
<wp:wxr_version>1.1</wp:wxr_version>
after the language tag. I can also confirm that the uploads directory is writable by the web server.
Will email you the XML file if that helps.
