HttpUnhandledException ASP.NET

Question

I have an ASP.NET site. If I make a page request, it works most of the time, but sometimes I get an HttpUnhandledException.

I tried to register errors, but from the error messages I can not solve the problem.

Stacktrace:

at System.Web.UI.Page.HandleError(Exception e)
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
   at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
   at System.Web.UI.Page.ProcessRequest()
   at System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context)
   at System.Web.UI.Page.ProcessRequest(HttpContext context)
   at ASP.default_aspx.ProcessRequest(HttpContext context) in c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\4e215a3c\72ef69da\App_Web_ylvnbciw.6.cs:line 0
   at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

Data:

System.Collections.ListDictionaryInternal

BaseException:

System.InvalidOperationException: The connection was not closed. The connection current state is open.
   at DbCategory.getParentCategories()
   at _Default.Page_Load(Object sender, EventArgs e)
   at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e)
   at System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e)
   at System.Web.UI.Control.OnLoad(EventArgs e)
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

TargetSite:

Boolean HandleError(System.Exception)

I have an idea that this is something about my og session that gets the variables, but I'm not sure about that. Does anyone have any idea what this might be?

Answer 1

Such errors are not due to an incorrect order - the connection was not closed.

, SqlConnection , , - .

---

: , - , - , . SqlConnection - , .

- , .

, singleton, :

private static object singleton;

lock (singleton)
{
    // Some manipulations with your server
}

Answer 2

Db (DbConnection, DbCommand, , ..) " ".

- 99% , , , .

Answer 3

VMAtm: , - , , . singleton...

public static SqlConnection getDbConnection() 
{ 
    if (sqlConn == null) 
    { 
        source = "data source=..."; 
        sqlConn = new SqlConnection(source); 
    }
    return sqlConn; 
}

?

, db singleton