Null reference on Entity Framework Migration

Question

When I user the Add-Migration command of Entity Framework migration I get the following exception:

System.NullReferenceException: Object reference not set to an instance of an object. at System.Data.Entity.Migrations.Extensions.ProjectExtensions.GetFileName(Project project, String projectItemName) at System.Data.Entity.Migrations.MigrationsCommands..ctor(Object project, Object startUpProject, String configurationTypeName, String connectionStringName, String connectionString, String connectionProviderName, PSCmdlet cmdlet)

Any insight?

Answer 1

I've seen this before when there are multiple projects in the solution and the "wrong" project is selected as the startup project. For example, somebody else reported that in an Azure hosted MVC3 website they had the Azure project as the startup project instead of the MVC project. Switching over to the MVC project as the startup fixed the issue.

Update: This has been fixed in EF5-beta2, which is now available on NuGet.