This is happening when I try to create the entity using a Create style action in Asp.Net MVC 2.
The POCO has the following properties:
public int Id
You can disable this implicit validation by setting the AddImplicitRequiredAttributeForValueTypes option on the DataAnnotationsModelValidatorProvider by adding the following to your Application_Start:
DataAnnotationsModelValidatorProvider.AddImplicitRequiredAttributeForValueTypes = false;
Further Reading: