The other day I received an error “System.InvalidOperationException was unhandled”
“The model backing the ‘XXXXContext’ context has changed since the database was created. Consider using Code First Migrations to update the database (http://go.microsoft.com/fwlink/?LinkId=238269).”
It turns out that I upgraded Entity Framework packages in only some of the projects within the solution and missed one project.
After I upgraded to the Entity Framework package to the latest one for that project, the error is fixed.
Lesson Learned: if you are going to upgrade one project’s Entity Framework NuGet Packages, be sure to verify all the NuGet packages in ALL of your solution projects have the latest Entity Framework package as well.