Moving the /databases directory solved the problem.
I first started mango (ma.sh start) as a user, and it appeared to start OK, but I could not login, so the database user creation must have failed !!
After moving the database, I started with
$sudo ./bin/ma.sh start
Connected to localhost:8080 and logged in as admin :-)
Fedora 27, by default uses the wayland display server, which will not let root processes attach to it, if it is running as an ordinary user.
Maybe a new option should be added to the env.properties to allow the server to start in "headless mode", so when I upgrade mango, I do not lose my "-Djava.awt.headless=true" hack
Thanks for the prompt help
Installed free-m2m2-core-3.3.0.zip on linux (Fedora 27).
I added a line to ma.sh as mango would not start, as it was trying to connect to the x11 display.
$ grep JAVAOPTS *.sh
I connect to http://localhost:8080 and get the mango login screen, but cannot connect as admin/admin.
The log on the terminal screen shows
WARN 2018-02-04T17:43:39,781 (com.serotonin.m2m2.web.mvc.spring.security.MangoAuthenticationFailureHandler.saveExceptionImpl:81) - Failed login attempt on user 'admin' from IP +0:0:0:0:0:0:0:1
Any tips for next steps