The issue happens because the SQLCMD.exe is installed in a path other than C:\Program Files\Microsoft SQL Server\.
To successfully use the DB Migration Tool, recreate the same installation path under C:\ drive:
- Duplicate the folder containing the SQLCMD.exe file to the folder where migration tool is searching (C:\ drive).
For example, if the SQLCMD.exe file is under D:\Program Files\Microsoft SQL Server\100\Tools\Binn, create C:\Program Files\Microsoft SQL Server\100\Tools\Binn\SQLCMD.exe. - Copy everything under D:\Program Files\Microsoft SQL Server\100\Tools\Binn\ to C:\Program Files\Microsoft SQL Server\100\Tools\Binn.
- Relaunch the DB Migration Tool and then update the Deep Security Manager DB Schema.