Operator '&&' cannot be applied to operands of type 'bool' and 'bool?' [duplicate]

Answer 1

You can try like this.

 foreach (var user in dataContext.Users
          .Where(u => roles.Contains(u.RoleID.Value) 
             && (u.isValid ?? false))) // note the bracket around (u.isValid ?? false)

Or

foreach (var user in dataContext.Users
       .Where(u => roles.Contains(u.RoleID.Value) 
        && (u.isValid.HasValue && u.isValid))) //you can use HasValue to check for null