The type of one of the expressions in the join clause is incorrect. Type inference failed in the call to 'Join'.

public List<data>GetData()

        {

            return (

                from ud in dbcontext.userdetails

                join td in dbcontext.taskdetails

                on new

                {

                   ud.uid ,

                }

                equals new

                {

                   td.uid.Value ,

                }

                select new data

                {

                    name = td.name,

                    amount = td.amount

                }

                ).ToList();

        }

Solution :- 

public List<data>GetData()

        {

            return (

                from ud in dbcontext.userdetails

                join td in dbcontext.taskdetails

                on new

                {

                   uid =  ud.uid ,

                }

                equals new

                {

                  uid = td.uid.Value ,

                }

                select new data

                {

                    name = td.name,

                    amount = td.amount

                }

                ).ToList();

        }