RE: SL 2015 upgrade from 7
I talked with our env team.
They are finding that you pretty much always have to reset the passwords. This appears to possibly occur because a different encryption is used in the different versions.
We wrote bug 34667 for this issue. It looks to be corrected in the next release. Notes says this.
When a SL 7x database set for SQL authentication with existing user passwords is upgraded to SL2015, the users cannot get into SL. In the Login screen they can enter their SL User ID do a PV and select a company and then enter a password. Click OK and get: Microsoft Dynamics SL has stopped working.
The workaround we have is this.
Clear the existing user passwords:
Run this against the SL system database:
Update userrec set password=''
The users can then log in with blank password and go to the Tools menu and set their passwords
or the Sysadmin can go into User Maintenance and set the user passwords.