LINQ2SQL switch to EF on reading a list of records

Answer 1

As far as I can see the problem is that Linq to Entities provider knows nothing about how to translate you custom method FetchUserInfo to ESQL.

If UserInfo is just a DTO and UserInfo.FetchUserInfo is a kind of Entity to DTO conversion method this would help

var data = query.AsEnumerable().Select(row => UserInfo.FetchUserInfo(row));

.AsEnumerable() invoke will result in materialization of query results to memory objects.