EF5:could not be created because the principal key columns could not be determined. Use the AddForeignKey fluent API to fully specify the Foreign Key

Question

We are using Entity Frame Work 5.0. and database MySQL. When we are try to migrate time get an exception.

could not be created because the principal key columns could not be determined. Use the AddForeignKey fluent API to fully specify the Foreign Key.

Answer 1

As explained here http://www.ozkary.com/2015/02/the-foreign-key-on-table-with-columns.html, you can have the issue when putting a FK to a table that is not part of your Db Context

So instead of doing

CreateTable(
    "dbo.App",
    c => new
    {
        Id = c.Int(nullable: false, identity: true),
        Name = c.String(nullable: false, maxLength: 150),
        RoleId = c.String()
    })
    .PrimaryKey(t => t.Id)
    .ForeignKey("dbo.MyRoles", t => t.RoleId)
    .Index(t => t.RoleId);

you should do:

CreateTable(
    "dbo.App",
    c => new
    {
        Id = c.Int(nullable: false, identity: true),
        Name = c.String(nullable: false, maxLength: 150),
        RoleId = c.String()
    })
    .PrimaryKey(t => t.Id)
    .Index(t => t.RoleId);

AddForeignKey("dbo.App", "RoleId", "dbo.Roles","Id");

Answer 2

Entity framework demands that relation is built between whole primary key in the principal table and corresponding columns (foreign key) it the dependent table.

Check if all your tables contain PRIMARY KEY COLUMN