If you are having trouble downloading the update because of a file conflict, Programfiles\Ardour4\Share\Ardour4\ArdourMono.ttf I had to stop the update, uninstall older version and then install the update with no problems…
Thanks, Ahmonster
You can ignore this warning or simply replace/overwrite the file.
From the Windowsinstall notes at http://nightly.ardour.org/
“If Ardour does not exit cleanly, uninstalling or replacing an existing installation will fail to replace font-files included with Ardour. You can ignore this or fix it by rebooting the system”