Create failed for user 'xx' error

"Create failed for user 'xx'. User or role already exists in the current database" is likely to occur when users were not properly mapped. it is fixed by running sp_change_users_login stored procedure

USE DatabaseName
GO

EXEC sp_change_users_login 'Update_One', 'myuser', 'myuser'
GO

This procedure with action 'Update_One', links the specified user in the current database to an existing SQL Server login. User and login must be specified.