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HomeHomeArchived Discus...Archived Discus...Developing Under Previous Versions of .NETDeveloping Under Previous Versions of .NETASP.Net 2.0ASP.Net 2.0value cannot be null. parameter name: virtualPath value cannot be null. parameter name: virtualPath
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6/11/2007 10:26 AM
 
dreggin

Joined: 7/24/2006
Posts: 10

Hi I am a developer that is relatively new to .net and developing in DNN.  I have a module that I have been working on that implements .net AJAX 1.0 and the toolkit.  The module also uses a lot of nested .ascx controls for various functionality and they are switched out as needed.  At the moment my biggest problems is that every once in a while when a postback occurs I get the error:

value cannot be null. parameter name: virtualPath

This seems to be almost random, it happens on different .ascx controls and at different times.  Any thoughts or ideas as to what potential causes may be would be appreciated.

Thanks!
 
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6/11/2007 1:16 PM
 
Brian Dukes


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Brian Dukes's Avatar

www.engagesoftware.com
Joined: 8/25/2006
Posts: 896

Can you look in the Log Viewer under the Admin menu to find the stack trace for that error?  That would probably help a lot, to know which method, specifically, is c ausing the error, and which of your methods is calling it.

Brian Dukes
Engage Software
St. Louis, MO
866-907-4002
DNN partner specializing in custom, enterprise DNN development.
 
New Post
6/11/2007 3:11 PM
 
dreggin

Joined: 7/24/2006
Posts: 10

Thank you for the response. I have posted my event log of an occurrence below, with some site specific information edited out.  When the module loads up, I call a subroutine that loads the appropriate control based on a session variable.  The modules access is restricted to logged in users, so if their session expires they are redirected to login.

AssemblyVersion: 04.05.01
PortalID: 0
PortalName: *Edited

UserID: 94
UserName: *Edited

ActiveTabID: 97
ActiveTabName: Tech Support
RawURL: /Support/TechSupport/tabid/97/Default.aspx
AbsoluteURL: /Default.aspx
AbsoluteURLReferrer: https://*Edited/Support/TechSupport/tabid/97/Default.aspx
UserAgent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
ExceptionGUID: 1ad3d67f-e17c-4aff-941d-43c3150d423a
InnerException: Value cannot be null. Parameter name: virtualPath
FileName:
FileLineNumber: 0
FileColumnNumber: 0
Method: System.Web.VirtualPath.Create
StackTrace:
Message: DotNetNuke.Services.Exceptions.PageLoadException: Value cannot be null. Parameter name: virtualPath ---> System.ArgumentNullException: Value cannot be null. Parameter name: virtualPath at System.Web.VirtualPath.Create(String virtualPath, VirtualPathOptions options) at System.Web.UI.TemplateControl.LoadControl(String virtualPath) at SBS_DNN_AJAXSupportDeskl.addSubControl() at SBS_DNN_AJAXSupportDeskl.Page_Load(Object sender, EventArgs e) at System.Web.UI.Control.OnLoad(EventArgs e) at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) --- End of inner exception stack trace ---
Source:
Server Name: WEBPRODUCTION1

Below is my code for loading the subcontrol in the module, again I am kind of new to this and I really appreciate you taking a look.

The AppRelativeVirtualPath="~/" thing has to do with some blogs that I read where people encountered similar issues, it has not fixed my issue.

  Sub addSubControl()Me.AppRelativeVirtualPath = "~/"

 

'testing for session failure

 

If Session(SDMode) = "" Or Session(SDMode) = Nothing Then

Session(SDMode) =

"TicketView"

 

End If

 

'this variable is for part of the path to the control, to allow for easy switching between the test and dnn environment

 

'just uncomment one line to switch

 

Dim strEnvPath As String

 

'strEnvPath = "~\"

strEnvPath =

 

 

"~\DesktopModules\SBS_DNN_AJAXSupportDesk\"

 

Dim ctlPath As String = ""

 

 

Select Case Session(SDMode)Case "TicketView"

ctlPath = strEnvPath &

"TicketView.ascx"

 

Case "UpdateTicket"

ctlPath = strEnvPath &

"UpdateTicket.ascx"

 

Case "AddTicket"

ctlPath = strEnvPath &

"AddTicket.ascx"

 

Case "AddCompleted"

ctlPath = strEnvPath &

"AddCompleted.ascx"

 

 

 

 

End Select

 

'Creates a control object, assigns it to the control we want and then loads it into the

 

'PlaceHolder.

controlToLoad =

 

Me.LoadControl(ctlPath)'We must assign a new id when switching controls

controlToLoad.ID = Session(SDMode)

phMainWindow.Controls.Clear()

controlToLoad.EnableViewState =

True

phMainWindow.Controls.Add(controlToLoad)

 

End Sub

Private

 
 
New Post
6/11/2007 5:25 PM
 
Brian Dukes


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Brian Dukes's Avatar

www.engagesoftware.com
Joined: 8/25/2006
Posts: 896

The error message seems to be saying that your call to LoadControl sends an empty string.  Instead of (or in addition to) using If Session(SDMode) = "" Or Session(SDMode) = Nothing Then Session(SDMode) ="TicketView", you should set a default case in your select case statement, so that you can make sure that nothing gets through.  The only other small thing that I notice is the direction of your slashes strEnvPath, I would use backslashes. I can't see any other gaping holes here, if that doesn't fix it, you can put a Debug.Assert statement right before the LoadControl statement to make sure that ctlPath isn't empty or nothing, and then you can monitor the debug output whenever it happens, and check the state of Session(SDMode), and anything else that might be problematic.

Brian Dukes
Engage Software
St. Louis, MO
866-907-4002
DNN partner specializing in custom, enterprise DNN development.
 
New Post
6/12/2007 10:12 AM
 
dreggin

Joined: 7/24/2006
Posts: 10

Thank you!

Before I wrote the reply to you I had not been aware of the event viewer within DNN, it makes debugging considerably easier.   The issue definitely appears to be a loss of session. I will add the changes you have recommended and maybe even consider viewstating the one variable.
 
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