First time bug submit so apologies if this is filed in the incorrect place. I recently setup and configured a domain controller and a file server with samba 4.1.6. (Come on Ubuntu apt repository) Authentication and accessing the drives is all okay and works, but i have an issue where users (connected in the domain) access to the "mapped drives" will periodically drop out. So i have log level turned on and when it happens to a particular user I decided to check the machine log level and see alot of entries with the following message; [2016/03/25 12:33:55.602091, 1] ../source3/smbd/sec_ctx.c:85(become_gid) WARNING: using gid -1 is a security risk Initially I thought this had something to do with my configuration, I was advised that it could be a bug that only samba developers could fix. You can see my initial question here at http://ubuntuforums.org/showthread.php?t=2320166&p=13468767#post13468767 Any ideas? Thanks Dan