Hello, I think I am running into the same problem. One thing i noticed is that in the MongoDB log file, the user that is trying to authenticate is whatever I entered in the install script, plus "@admin". So if my MongoDB username is "MongoDB", and i enter that in the install step, then my MongoDB log file shows "Supported SASL mechanisms requested for unknown user 'MongoDB@admin'", and the next line includes " Could not find user MongoDB@admin". Is that the expected username? I do show that there is a DB in my mongo called "admin". I tried manually adding users with same username and password, but no luck. I am also running Mongo as a windows service, and am even running that as an admin user with the same username and password just in case. I attached an output from the console and my mongodb log file. Thanks for any help or insight you could offer!