ayi <t>It usually happens because one of the following reasons:<br/> <br/> Entity Set is mapped from Database view<br/> <br/> A custom Database query<br/> <br/> Database table doesn't have a primary key<br/> <br/> After doing so, you may still need to update in the Entity Framework designer (or alternatively delete the entity and then add it) before you stop getting the error.</t>
