|
Hello all,
I receive this error when I click "cancel" on Login Form. I'm working with CSharp source code, but I don't make any changes.
Here is the exception:
---
An unhandled exception of type 'System.ObjectDisposedException' occurred in system.windows.forms.dll
Additional information: Cannot access a disposed object named "MainForm".
---
Thanks for your help.
Mirco Attocchi |
| MigrationUser 1 Thursday, June 19, 2003 10:34 AM |
New info:
This error appear only running CSharp Source on Framework 1.1, but I don't understand what does it mean.
Mirco Attocchi |
| MigrationUser 1 Monday, June 23, 2003 3:38 AM |
Hi,
Im having the same problem and cannot figure out what to change???
Have anyone found a solution to this?
Thanks
/Martin |
| MigrationUser 1 Monday, April 25, 2005 6:40 AM |
That is not absolutely correct. I am running VB.Net over Framework 1.1 and still getting this error. I am getting this error over a Form object that I am not disposing anywhere in my application rather keeping an instance and just calling its Hide and Show methods from time to time. After some time I get the following exception:
Exception: System.ObjectDisposedException
Message: Cannot access a disposed object named "frmStartScreen".
Object name: "frmSomeForm".
Source: System.Windows.Forms
at System.Windows.Forms.Control.CreateHandle()
at System.Windows.Forms.Form.CreateHandle()
at System.Windows.Forms.Control.get_Handle()
at System.Windows.Forms.ContainerControl.FocusActiveControlInternal()
at System.Windows.Forms.Form.SetVisibleCore(Boolean value)
at System.Windows.Forms.Control.set_Visible(Boolean value)
at System.Windows.Forms.Control.Show()
at MyApp.frmMain.ShowForm()
I am yet to find any clue for it. |
| Farhan Zia Wednesday, November 23, 2005 8:18 AM |
I was having a similar prob after I clicked the Close X at the top right of my second form windos...then tried to show it again.....the X unloads it....and since it is loaded at startup (when the first form opens), it cannot be shown again by using "form2.show()"
I just created a close button on the second for with the code "me.hide()" and disable the X at the top right of the form...form is then not unloaded but just hidden!
Hope this refers to your probelm...im just a beginner programmer so maybe this was NO help ;-D
|
| Mark Daly Thursday, December 01, 2005 8:27 PM |
hey, may be this will help.
You might wanna create an instance of an object for that window just before you tell to show it self. Something like this.
Private Sub mnuAddCompany_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles mnuAddCompany.Click
gfrmAddCompanyForm = New frmAddCompanies
gfrmAddCompanyForm.MdiParent = Me
gfrmAddCompanyForm.Show()
End Sub
Now if you see, I am making an object evertime a call is made to show the window.
Hopefully this help!!
Cheers!! |
| programmingsandhu Monday, February 13, 2006 12:10 AM |
I think you guys are not getting the overall problem - I've seen this happen a few times now, and it always has had something to do with the programmer wanting to have a logon form displayed before anything else. I bet that if you look in the constructor (Sub New for vb)of your main form (the form where you are calling Application.Run(MainForm)), you havesome calls tosome code ahead of the InitializeComponent() method that is added by default. Now what is going to happen is you are going to attempt to call Application.Exit(), or someform.Close() if there was something wrong with the logon, at which point everything will get disposed and then InitializeComponent attempts to set properties on your disposed form, and BAM object disposed exception.
btw,wtf isgfrm? seriously. |
| aaronxramirez Saturday, August 05, 2006 12:35 AM |
|
| Red bug Monday, March 19, 2007 9:53 PM |
I encountered a simular problem on Windows 2003 Server SP2. The error was:
Cannot access a disposed object named "TreeView".
Object name: "TreeView".
System.ObjectDisposedException: Cannot access a disposed object named "TreeView".
Object name: "TreeView".
at System.Windows.Forms.Control.CreateHandle()
at System.Windows.Forms.TreeView.CreateHandle()
at System.Windows.Forms.Control.get_Handle()
at System.Windows.Forms.TreeNode.get_State()
at System.Windows.Forms.TreeNode.get_IsExpanded()
at System.Windows.Forms.TreeNode.Remove(Boolean notify)
at System.Windows.Forms.TreeNode.Clear()
at System.Windows.Forms.TreeNodeCollection.Clear()
at LANDesk.ManagementSuite.ldPropertySheet.ldPropertySheetCtrl.UnloadPanels()
at LANDesk.ManagementSuite.ldPropertySheet.ldPropertySheetDialog.CloseDialog()
at LANDesk.ManagementSuite.SoftwareDistribution.WinUI.TaskScheduler.TaskNode.OnProperties()
Removing SP2 and reverting back to SP1 fixed the probelm.
|
| Technobabble80 Friday, March 23, 2007 4:50 AM |
Hello,
I have the same probleme with 2003 SP2 and Server Landesk8.6.
Could you help me ?
Thanks
|
| Bruno9 Friday, March 30, 2007 1:54 PM |
I get the same issue.
I'm creating a tab when a user selects a menu and then adding a form to that tab. I have an updater class that basically handles timing where a user can change update intervals... ontick it raises the event UpdateAll(). This works fine across the board for all the forms I create until I click the close tab. This ofcourse "disposes" the form. when I click the menu option that creates the tab w/ the form. It does it just fine... BUT.. when the UpdateAll fires it erros that form out with Cannot access a disposed object..
So as a recap
AppUpdater.vb - handles the timer,interval changes, the event for Updating
SubForm1,
SubForm2,
SubForm3 - All AddHandler Updater.UpdateAll,AddressOf initInternalUpdate
MainForm - Menu Option 1 creates a "SubForm1" tab in the tabControl. It then populates the panel under the new tab with SubForm1. The event fires a time later.. SubForm1 Updates. I close the tab. Click Menu Option1 again. The Subform1 loads. A short time later the UpdateAll event is fired and All the forms that are opened update like they're supposed to Except SubForm1.. which I closed and Reopened.
Now what I think is going down....
Everything is fine until the form disposes... then when I recreate the form... it loses the ability to receive ANY external calls. Example is a webBrowser control/DataGridView I have on the form.
if I do:
if SubForm1.isDisposed() then
SbFrm = New SubForm1()
SbFrm.MDIParent = Me
SbFrm.Parent = newCreatedTabItem
SbFrm.WebBrowser1.Navigate("about:blank") ' It says can't access disposed item
End if
.... BUT IT SAYS it can't... WHEN the form should be New ..
I have tried everything to work around this and Nothing works efficiently.. sure I can hide the tab but the form is still sitting there loaded in Memory. Not feasable.
|
| Chapley Watson Thursday, April 05, 2007 11:56 PM |
You guys will NOT believe how easy the answer is... thanks to a guy I worked with.. I did not go postal.. This issue is by design according to Microsoft.... The fix ( As bad as it is ) is to put the code: if isDisposed() then Return
As the first line in your Event Handler's code.
Rough Example
Public Class Form1
Inherits System.Windows.Forms.Form
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim clsA As New testA()
AddHandler clsA.UpdateAll, AddressOf UpdateMe
End Sub
Public Sub UpdateMe()
If IsDisposed Then Return
MessageBox.Show("Updated without Issue")
End Sub
End Class
Class testA
Private WithEvents Timer As New System.Windows.Forms.Timer()
Public Event UpdateAll()
Private Sub Timer_OnTick(ByVal sender As Object, ByVal e As EventArgs) Handles Timer.tick
RaiseEvent UpdateAll()
End Sub
Public Sub New()
Timer.Interval = 2000
Timer.enabled = True
End Sub
End Class
|
| Chapley Watson Friday, April 06, 2007 4:40 AM |
Hi everybody!
I got exactly the same problem, as Mirco. After several tries, I fixed it!
I think this error happens only if you try to dispose/close a form inside class constructor (even if you had already initialized components). A simply way to fix it is to move login method call to an event like MainForm_Load.
This way, I got no errors!
Regards,
Edgar Ferreira
|
| Edgar Tuesday, April 10, 2007 4:53 PM |
i'm opening all my sub-forms with singleton, now i extended them for forms:
http://netrsc.blogspot.com/2007/07/windows-forms-cannot-access-disposed.html |
| Roni Schuetz Saturday, July 21, 2007 3:22 PM |
I received this error due to class level variable that had the static modifier on it. When I resued the object, it was not null, but it as Disposed!
I changed the test on the variable from x == null to x == null || x.IsDisposed. In both cases, I re-instanciated the object.
Regards,
Richard
|
| greatwhitenorth Tuesday, August 14, 2007 9:26 PM |
I got this error while trying to set a global constant (defined in a module) and then showing up form2. here is vb.net code =========================================================== USERID = Convert.ToInt64(DirectCast(sender, LinkLabel).Tag.ToString()) 'setting global constant Dim frm As New frmUsersDetail 'creating form2 frm.MdiParent = Me.MdiParent frm.Show() Me.Dispose(True) ' <-- HERE IS Cannot access a disposed object named "linkLabel" EXCEPTION
===========================================================
amazingly, there is no "linkLabel" control in the entire project. wonder how compiler found this name  anyways, one quick and dirty solution is so dispose the form by passing "False" as argument and not "True". here is vb.net code: ============================================================ Me.Dispose(False) ' <-- YES, ITS WORKING hope this helps someone  |
| sourabh1982 Wednesday, November 21, 2007 6:07 AM |
hello everyone,
i was looking to the problem posted and the solutions....but the one i like is your solution Mr.Edgar.
atleast it has solve my problem so smoothly.
thanks
|
| GameOver_1 Wednesday, August 06, 2008 10:45 AM |
Thanks a lot, even i am also facing the same problem. This article helps me a lot . i solved this problem like if (IsDisposed == false)
this.Show();
else { frmReminders_Load(sender, e);// Call the Load event when form is disposed.
}
Thank u |
| SGRavi Monday, February 02, 2009 12:18 PM |
This really helped me..................
Thanks a lot..
Regards
Vijay |
| Vijay Koul Wednesday, April 01, 2009 6:39 AM |
Hey Thanks sandhu
that was a really simple and easy solution .had the same problem but it is solved now. |
| gurpureet Sunday, April 19, 2009 8:30 AM |
Hey everybody just try this code.................. i think this will help u out from the problem.
private void Form1_Load(object sender, EventArgs e)
{
//make a condition to call this
this.BeginInvoke(new MethodInvoker(UnloadMe));
}
//call this function out side
private void UnloadMe()
{
this.Close();
}
-- With Regards Deepak Anmol Sr Developer MCTS, MCP |
| Deepak Anmol Monday, August 24, 2009 12:07 PM |
index > Windows Forms Sample Applications > Cannot access a disposed object named "MainForm"