Good suggestion, however, nt so accurate in all cases. I figure one out. Please you need to make sure you run "enable-migrations" using PM windows in Visual Studio, and Migration folder would be added to you project.
Make sure the two c# class files added to the folder on will contain all your models and their respective properties.
If you have all that build the solution, and publis for deployment.
The logic is that the existing metadata cannot be overwritten because your application has no metadata to replace the current. As a result you are getting this error "The model backing the context has changed since the database was created"