c# - Linq error: Unable to create a constant value of type -

I am trying to execute the following linq query:

  result = (to Users in the context. VwUsers join board on board in the board on the board. National equivalent to any board, select any user). List ();  

But I'm getting the following exception:

System.NotSupportedException: Unable to create a constant value of 'DataAccessLayer.User' type.

More info:
Board Member is the result of follow-up Linq query:

  Var board member = (from the context of the apartment group where complex.grpId == complex ID select complex). first (). the user;  

I am trying to get a list of vwUsers from DB, and trying to do my code below:
1. List Receive user from db (this type is user .) 2. Convert the previous list to vwUser s list.

try it,

  var boardMembers = (on campus premises Select apartment group where complex.grpId == complexId.Custom) .FirstOrDefault () user;  

- Do this for the required result

  var result = c.wwUsers in context where boardMember. Selection (x => x.nationalNo) .Contains (c.nationalNo) Select c;