Q:

New User in SSMS Can't Login

I have installed SSMS (v17.1), created a new login at Security -> Logins, changed mode on the server (server: OWNER) to mixed mode.  But the username/password combination doesn't seem to work.  New Database Query -> SQL Server Authentication -> enter username/password and get error:  Cannot connect to OWNER. Login failed for user 'myusername'.  HELP!

A:

According to Change Server Authentication Mode when the authentication mode is changed the server has to be restarted. Until restart SQL Server is still using Windows only authentication mode and that is what we can read is SQL Server error log as the reason of 18456 "login failed for user (...)"

