[Solved]-linq count error: DbExpressionBinding requires an input expression with a collection ResultType. Parameter name: input-LINQ,C#

you should use 'by new' after 'group'. i hope this will help you.

var entries = from entry in _db.entries
    group entry by new { entry.name } into groupedbyname
    select new
    {
         groupedbyname.key.name,
         numberofcomments = groupedbyname.count(x => x.name != null)
    };