The specified type member 'IsLock' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported.

var query = from C in objDb.GetDb<A>()
join a in objDb.GetDb<B>().Where(m => m.ComputerID != null)
on C.Email equals a.Email
select new C
{
};

EF 执行错误：The specified type member 'IsLock' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported.

原因：new 的时候要初始化大括号的属性值

修改后

GridDto<DownRegistrationDto> entityDb = new GridDto<DownRegistrationDto>();
var query = from C in objDb.GetDb<a>()
join a in objDb.GetDb<b>().Where(m => m.ComputerID != null)
on C.Email equals a.Email
select new C
{

　　 DID = C.DID, ProductID =C.ProductID,ProductName =C.ProductName,FepVersion =C.FepVersion
};