c# - An unhandled exception of type 'System.InvalidCastException' -

my c# vs2015 application throws exception:

system.invalidcastexception unhandled

message=unable cast object of type 'system.data.entity.infrastructure.dbquery`1[adonet4linqtoentities.customer]' type 'system.data.objects.objectquery'.
source=adonet4linqtoentities

the error occurs in line defines query variable:

var customers = c in de.customers                 c.orders.any(o => o.orderamount > 150)                 select c;  string query = ((objectquery)customers).totracestring(); 

my assumption objectquery prompting exception.

i tried string query = ((dbquery)customers).tostring() instead, works in vs2013, resulted in same exception.

why vs2015 throw exceptions these query approaches?

because customers not objectquery want objectquery<customer> remove projection (the select).

change to

var customersquery= c in de.customers                     c.orders.any(o => o.orderamount > 150);  string query =  customersquery.totracestring(); 

i took out naming lexical ambiguity naming customersquery.

see objectquery.totracestring method (system.data.objects) more information.