Why do I get error "Login failed for user 'myuser'." when using the SQL Server ODBC driver?

Check that the User and Password attributes for the ODBC data source in odbc.ini specify a valid SQL Server user name and password.

This error also displays if you try to connect to SQL Server with a valid Windows user name and password but no corresponding SQL Server login exists. For example, SQL Server Setup creates a login named BUILTIN\Administrators that allows members of the local Administrators Windows group to access SQL Server. As a security measure, the database administrator may delete this login and members of this group will then need individual SQL Server login accounts to access SQL Server.

Ask your database administrator to create a SQL Server login for you that uses Windows authentication to validate your connection details.