internal connection fatal error in c#

Question

I am using thread because when open a form the fill the background data in combobox and store procedure combobox data successfully but issue is when I open a form and immediately I press the close button then give an

error like:

 

internal connection fatal error

connection close

 

I am trying but not able to solve this error

 

please help

 

myform.cs

public void ShowForm()
{
   this.Show();            //here open a form
   WorkerSetControl(() => Load_Datas());   //call a thread
}

Thread ObjThreads;

private void WorkerSetControl(Action methodName)
{
    ObjThreads = new Thread(new ThreadStart(() => methodName()));
    //ObjThread.IsBackground = true;
    //ObjThread.SetApartmentState(ApartmentState.STA);
    ObjThreads.Start();

    //if (!ObjThread.Join(TimeSpan.FromSeconds(30)))
    //{
    //    ObjThread.Abort();
    //    throw new Exception("More than 30 secs.");
    //}
}

public void Load_Datas()
{
    _product.FillForCombo(_prdcode, _prdtype, UltCmbprdType.Text);

    _product.SetColumn(_PrdMast.TableNameProductList, "CODE,DESC,RG", "90,100,200");
    _product._SetDataBinding(_ProdDS,  TableNameProductList, true);
}

protected override void OnFormClosing(FormClosingEventArgs e)   //Here I am closing a form
{
    this.Enabled = false;   // or this.Hide()
    //ObjThreads.IsBackground = false;
    //Thread.Sleep(1);
    //_product.ds = null;
    this.Hide();
}

_Prod.cs

public DataSet DS
{
    get { return _DS; }
    set { _DS = value; }
}

public void FillForCombo(string pStrCompCode, string pMast_Type, string pStsOrdType = "")
{
    Ope.Clear();

    Ope.AddParams("Cmp_Code", pStrCompCode);
    Ope.AddParams("M_Type", pMast_Type);
    Ope.AddParams("P_TYPE", pStsOrdType);

    //if(ConnectionState.Open != ConnectionState.Closed)
    //{
    //if (Ope.IsConnectionCheck(Ope.EnumServer.servername) == true)
    //Ope.OpenConnection(Ope.EnumServer.servername);
    Ope.FillDataSet(Ope.EnumServer.servername, DS, TableNameProductList, Spp.usp_PrdsFillForCombo, Ope.GetParams());
    //here give an error internal connection fatal error / connection closed error when open a form and immidiately i close a form then give an error
}

OperationSql

namespace DataLib
{
    public class OperationSql : GlobalSql
    {
        public static CultureInfo CultureInfoUS;
        public static Hashtable HTParam;
        public static int IntParamCount;

        public OperationSql();

        public static void CCon(EnumServer ServerCon);
        public static void CCon(SqlConnection pConn);
        public static void Clear();
        public static void CloseConnection(EnumServer ServerCon);
        public static void ClsRed(SqlDataReader pReader);
        public static bool OpenConnection(EnumServer ServerCon);
        public static void FillDataSet(EnumServer ServerConn, DataSet pDataSet, string pTableName, string pProcedureName, SqlParameter[] pParamList, bool pSetTime = false, bool pBlnCatch = true);

        public enum EnumServer
        {
            servername = 1,
            servernamesd = 2
        }
}

when i open a form and after sometime I press close button then not give an error but when I open a form and suddenly press a button then give an error

 

internal connection fatal error / connection close error / object referance not set to an object

 

I know why give an error because thread running in background and I press the close button quickly when open a form that is problem

 

please help