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

Solution 1:

You cannot use properties that are not mapped to a database column in a Where expression. You must build the expression based on mapped properties, like:

var date = DateTime.Now.AddYears(-from);
result = result.Where(p => date >= p.DOB);
// you don't need `AsQueryable()` here because result is an `IQueryable` anyway

As a replacement for your not mapped Age property you can extract this expression into a static method like so:

public class clsProfileDate
{
    // ...
    public DateTime DOB { get; set; } // property mapped to DB table column

    public static Expression<Func<clsProfileDate, bool>> IsOlderThan(int age)
    {
        var date = DateTime.Now.AddYears(-age);
        return p => date >= p.DOB;
    }
}

And then use it this way:

result = result.Where(clsProfileDate.IsOlderThan(from));

Solution 2:

A lot of people are going to say this is a bad answer because it is not best practice but you can also convert it to a List before your where.

result = result.ToList().Where(p => date >= p.DOB);

Slauma's answer is better, but this would work as well. This cost more because ToList() will execute the Query against the database and move the results into memory.

Solution 3:

You will also get this error message when you accidentally forget to define a setter for a property. For example:

public class Building
{
    public string Description { get; }
}

var query = 
    from building in context.Buildings
    select new
    {
        Desc = building.Description
    };
int count = query.ToList();

The call to ToList will give the same error message. This one is a very subtle error and very hard to detect.

Solution 4:

I forgot to select the column (or set/map the property to a column value):

IQueryable<SampleTable> queryable = from t in dbcontext.SampleTable
                                    where ...
                                    select new DataModel { Name = t.Name };

Calling queryable.OrderBy("Id") will throw exception, even though DataModel has property Id defined.

The correct query is:

IQueryable<SampleTable> queryable = from t in dbcontext.SampleTable
                                    where ...
                                    select new DataModel { Name = t.Name, Id = t.Id };