sql server ExecuteReader requires an open and available Connection. The connection's current state is closed -

i using multithreaded application extract data database , after few minutes of running start exception or sql timeout exception. code below:

    public static list<flightinfo> flightinfoallpricesperdayforroute(string from, string to)     { // create object array datareader         list<flightinfo> arr = new list<flightinfo>();         using (var conn = new sqlconnection(sconnectionstring))         {             using (var command = new sqlcommand("flightinfoallpricesperdayforroute", conn)             {                 commandtype = commandtype.storedprocedure             })             {                 conn.open(); command.commandtimeout = 150;                 command.parameters.addwithvalue("airportfrom", from);                 command.parameters.addwithvalue("airportto", to);                 // command.parameters.addwithvalue("date",  dt);                   //execute stored procedure                 using (idatareader dr = command.executereader())                 {                       flightinfo obj;                      while (dr.read())                     {                         obj = new flightinfo();                         obj.flightinfoid = (int)dr["flightinfoid"];                         obj.airportfrom = (string)dr["airportfrom"];                         obj.airportto = (string)dr["airportto"];                         obj.timedeparture = datetime.parse(dr["timedeparture"].tostring());                         obj.timearrival = (datetime)dr["timearrival"];                         obj.price = (short)int16.parse(dr["price"].tostring());                         obj.dateadded = (datetime)dr["dateadded"];                         obj.carrier = (string)dr["carrier"];                          arr.add(obj);                     }                      dr.close(); dr.dispose(); conn.close(); conn.dispose(); command.dispose();                   }             }         } return arr;     } 

i have added teh following connection string improve timeout problem still getting errors:

   min pool size=200;max pool size=32767;asynchronous processing=true;   connect timeout=150; 

the stored procedure simple don't think there problem there:

select *,  dateadd(dd, 0, datediff(dd, 0, timedeparture)) flightdate flightinfo   airportfrom = @airportfrom , airportto = @airportto , timedeparture > getdate() -- future flights order flightdate asc, price asc 

i've tried running check sql connections 'the user not have permission perform action.' error

  select * sys.dm_exec_connections 

any suggestions appreciated!

your code looks ok - suggest on database server problem. if stored proc takes long time run and/or causes lot of locking in tables, these problems (especially if called frequently). query optimization in order.

fyi - don't need 'using' block around sqlcommand object. also, there no need call 'close' , 'dispose' on reader , connection objects - 'using' handle you.