Asp.net - NullReference On Object In Code Behind After AsyncPostBack Using UpdatePanel?
Feb 20, 2012
I'm building a simple game in an ASP.NET/VB.NET web app. The game has a UI made up of several ImageButtons. The web page's code behind file holds an instance to the game object which will manage each turn taken by players. Everything worked when the Game object's methods were Shared. The problem occurred after refactoring to make the game object work as an instance instead of a shared class. Now, when the action returns to the code behind, the instance of the game object is nothing.
The code bits:
Public Class _Default
Inherits System.Web.UI.Page
Private _gamePanel As Panel
[code]....
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Jun 24, 2011
I have a fully dynamiclly generated page that has a set of linkbuttons basically switching views in a UpdatePanel. All that is working great except for when I have a button that is generated that needs to invoke a function to manipulate the data in the Update Panel.
[code]...
So the problem is when the page_init is executed it does not know which linkbutton was selected so it never recreates the button and in turn never fires the event. I have seen people use the session to store the list of controls and/or the current frame but I don't see that as an acceptable solution. Surely there has to be a way to do this.Is there no way I can get the ScriptManager's current/previous step information outside of the Navigate event?Asp.net 4.0 with latest ajax toolkit.
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Jan 5, 2010
I am getting this error when I try to print my report. Here is my print code.
Private Sub PrintToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PrintToolStripMenuItem.Click
Dim Print_Dialog As New PrintDialog
[code].....
Here is my error: System.NullReference Exception: Object reference not set to an instance of an object.
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Feb 7, 2011
When the following executes, I get the error 'NullReference Exception' - Object reference not set to an instance of an object. TestClass has Get and Set methods for the integer property TestWord.How should the following be changed to let me set TestWord in six elements of TArr?
Dim TArr(5) As TestClass
For i As Integer = 0 To 5
TArr(i).TestWord = i * 10
Next
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Nov 23, 2011
"object reference not set to an instance of an object" this is the error i got in the code below: ' Use SendMessage to copy the data to the clipboard Then transfer the image to the picture box.
[Code]...
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Aug 17, 2010
I am trying to trying to setup an updatepanel to update every X seconds, the problem is I don't want the control to actually refresh unless there is new data. So I currently have a child updatepanel in a parent UpdatePanel, the child updatepanel gets refreshed by a timer. But I can't seem to find a way to trigger the parent panel to update. Again, only when certain conditions(data changed) are met.
Sample Code:
<asp:Timer ID="Timer1" OnTick="Timer1_Tick" runat="server" Interval="10000"></asp:Timer>
<asp:updatepanel id="upParent" runat="server" UpdateMode="Conditional">
[Code].....
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Mar 8, 2011
i got this code from the net , but i can't make this code work on the system i am programming so, i used the same codes to another system and it worked, when i tried using it to my system, it failed, so i started a new program and it still fails... what is wrong with my program? here is a sample of the code:
[code]...
whenever i run the program, it compiles, but when i click the commit button, this message appears "NullReference Exception was unhandled Object reference not set to an instance of an objects" and it points to .NewRow
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Jan 14, 2010
[Code]...
VS 2008 Null error "NullReference object was unhandled"
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Oct 20, 2011
When an UpdatePanel Calls a method in server and for example this method change textBox1.Text = "12312"
and this textBox1 was out of updatePanle scope it dosn't change it text till a postback happend to the page
so I need after that calculation and chaging the Textbox's text in the server, I need to forcepage to do postback
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Jun 13, 2012
I have a RadGrid in a page which has a master page with an UpdatePanel wrapped round the Content. I have successfully run RegisterPostbackControl for the Export buttons on it on first load, thus:
[Code]...
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Sep 27, 2010
I have a function that gets a string passed to it.When testing the function, I'm getting a null reference exception on the string parameter that gets passed to it, even though the string is not null, I don't understand why I'm getting this error.I used a dummy value to verify both the string parameter in the SelectSingleNode function and the newValue string parameter being passed to my function and they both contain values, so I don't understand why it's throwing a null reference exception. Just for clarity, the purpose of the function is to write values back to the nodes of an XML file.[code]
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Mar 30, 2009
I have a function that gets a string passed to it. When testing the function, I'm getting a null reference exception on the string parameter that gets passed to it, even though the string is not null, I don't understand why I'm getting this error. I have a screen shot belowI used a dummy value to verify both the string parameter in the SelectSingleNode function and the newValue string parameter being passed to my function and they both contain values, so I don't understand why it's throwing a null reference exception. Just for clarity, the purpose of the function is to write values back to the nodes of an XML file.UPDATE
Private Sub setValue(ByVal nodeToMod As String, ByVal newValue As String)
''Test writing to xml config file
Dim dummy As String = "Config/" & nodeToMod
[code].....
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Aug 14, 2010
with datagridview1
while looping through all the cells
i am trying to allot a cell value to another cell value basing on some conditions
& finally delete one column.my code is as fallows
Dim i, x As Integer
i = 0
x = Me.DataGridView1.Rows.Count[code]....
error i am getting is : Object reference not set to an instance of an object.it is extremely surprising for me the same code has worked nice for me but why & how the same line of code is generating this error.
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Apr 18, 2010
I got the following code from the demo code samples and just changed the textbox names. But it throws an error:
Private Sub Fill_TextBox()
Dim Num As Integer
Dim DSet As DataSet
[code]....
The error is:
System.NullReferenceException:Object reference not set to an instance of an object.
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Mar 4, 2010
Here is the code for the button click event;
Protected Sub CompetenciesButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles CompetenciesButton.Click
Dim con As String = WebConfigurationManager.ConnectionStrings("foo").ToString()
[code].....
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Nov 28, 2011
I'm converting an application from VB6 to VB.NET, and am required to declare and initialise some controls in code (control arrays). I have it declared globally, so other forms can access the data stored within them, and then I try to manipulate them inside the Form_Load() sub:
Public lblDataZone() As Label
Private Sub Form_Load() Handles Me.Load
lblDataZone(0) = New Label
[code]....
The error I get says "Object reference not set to an instance of an object". I feel like I'm missing something huge here, but what's wrong with it?
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Jun 29, 2011
[code].....
I m getting an error NullReference Exception was handled at this line of code
Dim snmp As New SimpleSnmp
snmp = New SimpleSnmp(host, community)
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Oct 13, 2011
The second Case in the first Sub is the one giving the error message.The second Sub is the part I (Removing the Label so that it can be recreated later) fix this code block? I do not know the correct way of removing or desposing a Label, as you can see the Label
Public Class Form1
'<<< Indecating if the app. is in Reading, Editingor AddingNew.>>>
Dim ModeIndecator As String = "Reading"
[code].....
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May 2, 2012
I have a code section in my current active directory program in which it gives the error in the title above at the line:
If results.Path = "" Then from below code:
Dim results As SearchResult = Nothing
[code].....
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Jan 26, 2011
coming from this question i was wondering why:
[Code]....
'this throws an "Object reference not set to an instance of an object"-Exception'
[Code]....
A CType(obj, Boolean) would evaluate to False(just as CBool(obj)), i think because the compiler uses a helper function, but that is not my theme. Why does casting Nothing to Boolean evaluates to False, whereas casting an object that is Nothing to Boolean throws an Nullreference-Exception? Does that make sense?
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Sep 26, 2009
I keep Getting a NullReferenceException Error but I have declared a NEW structure. See below:
Structure ISACReply
Public RTD As ArrayList
Public SAC As ArrayList
Public DRT As ArrayList
[code]....
When I try to execute the subroutine "calltest" I get a NullReferenceException in the line that says " rv.DRT.Add("HELLO") " even though I have set rv to an instance of ISACReply using NEW.
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Sep 23, 2011
I am developing a windows application in vb.net and getting an error of system.nullreference exception.I am trying to insert data in the database, insertion occurs in the first go. But, when i stop the porgram and re-run, i get the exception.
Imports System.Data
Imports System.Data.OleDb
Imports System.EventArgs
[code]....
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Mar 7, 2011
I'm getting a design time NullReferenceException on Dim db As Database = DatabaseFactory.CreateDatabase()and I can't figure out what to do about it. Has anyone experienced this problem or know the solution?
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Jan 19, 2012
I stumbled upon the statement "If Me IsNot Nothing" several times. Often I find this in WinForms samples.I dont't get the sense or meaning of this line. "Me" refers to the current Object or Form, so if I am executing this line "Me" can't be Nothing. Or am I missing something here?Is there a way that Code of an Object is executing even when the current Object is Nothing?
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Nov 19, 2010
I have a TreeView with a parent node and two children node. Each of the nodes contain a checkbox stored in a TreeViewItem. I want the two children node checkboxes to be set to IsChecked=true when the user checks the parent node and I want the two children node checkboxes to be IsChecked=false when the user unchecks the parent node.
[Code]...
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Jul 28, 2009
I created a typed dataset a day or so ago, then I added a whole bunch of tableadapter/tables with some relationships etc... suddenly out of nowhere it decides my dataset "is not defined". everywhere in my code where i use this dataset now has an error. I tried not to pull out my hair and do a Clean then Rebuild solution... out of nowhere it just refuses to generate code. Object reference not set to an instance of an Object. It would be nice if it was my object so i could find it but it's not.
Curiously I also lost the little database icon on the dataset in the solution explorer.I can still open it in the designer and preview my queries etc... it just wont make the code. it's driving me insane. anyone got a solution?
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Oct 13, 2010
I have a page with Ajax Tab controls, within one of the tabs is a webcontrol that as a Telerik RadGrid, with Edit forms pointing to another web control. That edit form also contains Ajax Tabs and on one of those tabs, there is an Ajax modal popup of yet another webcontrol.The initial webcontrol works fine when used on it's own page, but the edit form fails to appear when the control is used within the Ajax Tabs as desired. The script manager is throwing the following error:
Microsoft JScript runtime error: Sys.InvalidOperationException: Could not find UpdatePanel with ID 'xxx'. If it is being updated dynamically then it must be inside another UpdatePanel.
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Feb 17, 2012
When i put
<asp:FileUpload ID="FileUpload1" runat="server" class="multi" />
<br />
<asp:Button ID="btnUpload" runat="server" Text="Upload All" /> outside the update panel everything works fine,but as soon as i put it back into the update panel...it stops working.
ASPX CODE
[Code]...
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Jun 9, 2011
How can i set the cursor focus on the top of the page when I clicked Update button.
Update button is under UpdatePanel
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Jan 3, 2011
I'm currently having an issue where an updatepanel does an async postback and loses the tab order when the partial postback occurs.When you run through the tabs the tab order works correctly, but then you press a button and the partial postback occures the tabindex is reset.
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