When using dispinterface types, you must always be sure to include a GUID specification for them.

program Produce;

  type
    IBase = dispinterface
    end;

begin
end.

In the example shown here, the dispinterface type does not include a GUID specification, and thus causes the compiler to emit an error.

program Solve;

  type
    IBase = dispinterface
    ['{00000000-0000-0000-0000-000000000000}']

    end;

begin
end.

Ensuring that each dispinterface has a GUID associated with it will cause this error to go away.