Doing a POST to the ws (at least on puid submit and barcode submit), I get a stacktrace if I don't set
f.add_header('Content-Type', 'application/xml; charset=UTF-8')
rather than an error message
As far as I can tell, there is no content-type header, rather than an incorrect one.

The immediate error is
Caught exception in MusicBrainz::Server::Controller::WS::2::Recording->recording_submit "
no element found at line 1, column 0, byte -1:
17^
2860272
at /usr/lib/perl5/XML/Parser.pm line 187"

I can provide further stacktrace and data if needed