I have MariaDB 5.5, 10.0 and 10.1 installed (as Windows services named 'maria55'. 'maria10' and 'maria10_1' ) and always update them to latest soon after an update is available. Yesterday morning I installed 10.0.16 on top of 10.0.15 using the .msi installer.  When I tried to connect to it a few hours later it was not possible.  I thought the service might not be running. It wasn't.  Actually it did not exist anymore at all!  "net start maria10" returned "service does not exist" (and indeed it did not appear in Windows "services management" interface). I copied the /datadir, uninstalle , did a fresh install of 10.0.16d (choosing the option not to upgrade any existing server) and copied the old /datadir back. Now Maria 10.0(.16) works again.

But now I see that the 'maria55' service is also gone from the system. Files are intact. I can repeat the exercise I did with 10.0 of course or install service again from commandline. Not a big problem, but very annoying and waste of time. 

MariaDB 10.1 installaton is not affected. 5 diiferent Oracle/MySQL servers (from 5.0 to 5.7) also are not. I need all those instances for application testing.

Questions: 
* Has somebody else experienced this?
* Has somebody replaced @wlad as maintainer of Windows installers? @wlad was the only person who ever was able to write reasonable MySQL/MariaDB installers. So I would regret that.

It is perfectly legal on Windows to have multiple MariaDB servers simultaneously running as Windows services. They won't conflict  as long as service name, port, basedir and datadir are all different. What happens with one should not affect another. I the installer does not respect this, it is a bug. 

-- Peter 
-- Webyog