I updated my Mame version to 165b (was 149b before) and I noticed Mgalaxy only create a 109 bytes file, with this contents :
<?xml version="1.0" encoding="utf-8"?>
<dbase name="Multi-system [MAME]" version="0.165 (Aug 26 2015)" />
(I checked the size during the creation of the database and it was more than 100 Mb, then only 109 bytes.
Does someone have a valid database for the last Mame version, by the way? (Actually, I'm using the 149b one).