Windows Forms App: System.NullReferenceException Error
May 22, 2012
I have been trying to figure out the source of error in my application. What this function (GetConcentrations()) is to display data from my database onto a DataGridView. The function is called in the PageLoad but works fine but when I call it in another Sub, I get this error.
Here is the code:
Private Sub GetConcentrations()
Dim conString As String = ConfigurationManager.ConnectionStrings("dbAsthmaConnectionString").ConnectionString
Me.dataAdapter = New SqlDataAdapter("Select * from tblConcentrations", conString)
An unhandled exception of type 'System.StackOverflowException' occurred in System.Windows.Forms.dll it also says make sure you do not have infinate loop or infinate recursion il give all code in order that they are executed in Check the chechbox and it disables all irelevent stuff and populates the combobox
Private Sub CheckBox_Spray_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CheckBox_Spray.CheckedChanged If Me.CheckBox_Spray.Checked = True Then
When I run my project I get "An unhandled exception of type 'System.StackOverflowException' occurred in System.Windows.Forms.dll"
Public Class frmViewReport Dim objForm As New frmViewReport Private Sub frmViewReport_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load objForm.ViewReport("C:a2.rtp", , "@parameter1=test�mter2=10")
I have the following code running, the first time I change the selected index, everything runs smoothly. However, if I try to change the selected index again, nothing happens and the subcategories combobox values do not change.
Private Sub cboMainCategory_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboMainCategory.SelectedIndexChanged '* make sure the combobox is fully loaded
I keep getting an eroor this error says: An unhandled exception of type 'System.ArgumentOutOfRangeException' occurred in system.windows.forms.dll Additional information: Specified argument was out of the range of valid values.
Option Strict On Public Class frmWeeklyReport Inherits System.Windows.Forms.Form
I am working on a card game, and i get this werid error:
A first chance exception of type 'System.Reflection.TargetParameterCountException' occurred in System.Windows.Forms.dll
The code that is cousing this error is:
Private Delegate Sub ShowcardDelegate(ByVal test As String, ByVal objtest As Object, ByVal value As Boolean) Private Sub Showcard(ByVal test As String, ByVal objtest As Object, ByVal value As Boolean) If objtest.InvokeRequired Then
I get this: Base class 'System.Windows.Forms.Panel' specified for class 'MenuButton' cannot be different from the base class 'System.Windows.Forms.UserControl' of one of its other partial types.
OK, in it's simpest terms, I have a custom object (all string Items) which I add to a list of those items. The list is declared as a global variable. One form updates the list, another contains a dataGridView (vs.net 3.5) that displays the list items. The view displays the correct data. For some reason, if I select a header in the dgv before it's populated, that's fine, but if I select it (click anywhere with the mouse) it bugs out with an Index = -1 error from the System.Windows.Forms. CurrencyManager.get_Item(Int32 index) bit.
I have the code which checks if there is a selected tab
Private Function GetBrowser() As WebBrowser If TabControl1.SelectedTab IsNot Nothing Then For Each c As Control In TabControl1.SelectedTab.Controls If TypeOf (c) Is WebBrowser Then Return c
there is one problem here the root node on the line "GetDirectories(info.GetDirectories(0, rootNode))" here is the error "Error 1 Value of type 'System.Windows.Forms.TreeNode' cannot be converted to 'System.IO.SearchOption'."
ERROR:Error'Value' is not a member of 'System.Windows.Forms.TextBox'.
My Code:
Private Sub TextBox2_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox2.TextChanged If TextBox3.Value > TextBox2.Value Then
I grabbed an example program to modify for my needs to grab data from a Word doc and transform to XML. Right off the bat I get multiple errors. [Code] I am getting Error Type 'System.Windows.Forms.Application' has no constructors.
I am adapting this code from excel vba to a Visual Studio program I am writing that will list files that are relevant to given information. I keep getting an error about filesearch not being a memeber of 'system.windows.forms.application' on line fs = Application.FileSearch, I have read and saw that I should be using the DIR function...
Sub SearchForForms() Dim fs As FileSearch ', ws As Worksheet, i As Long Dim SearchFileName As String fs = Application.FileSearch <~~~ ERROR[code]....
I've just started learning VB.NET with VS 9.0; a small application I'm working on keeps returning an "A first chance exception of type System InvalidOperationException occurred in System Windows Forms dll" error from the Immediate Window. The application has almost zero functionality so far, it consists of a menu strip with:
File About |Open |Save |Save As |Quit
The only code I have written opens an Open File dialog, a Save As dialog, an About window with background sound and an OK button, and the Quit button which exits.
Since there is almost no code for me to search through, I can't understand why there would be an error. The program runs just fine when I'm debugging it too.
I have a panel with some controls in it (several textboxes, a slider, 2 buttons, and a small groupbox).. When I click a button, I want all of the textboxes within the panel to be readonly... So I have this code: [code] When I run it though, I get the following error:Unable to cast object of type 'System.Windows.Forms.Button' to type 'System.Windows.Forms.TextBox'.If I remove a button, it moves on to give me the same error but for a label..
I'm trying to run a simple database and im getting a "System.NullReferenceException" error ) & "Additional Information:Object reference not set to an instance of a object" .
txtItemName.Text = rowCurrent.Item("ItemName") <-- highlighted in yellow
Code is as follows:
vb.net Imports System.Data.OleDB ---------------------------------------------------- Public Class Form1
Unable to cast object of type 'System.Windows.Forms.MouseEventArgs' to type 'System.Windows.Forms.DataGridViewCellMouseEventArgs'.
Private Sub NoteGrid_CellContentClick(ByVal sender As System.Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles NoteGrid.CellContentClick Try
with this code dont know wht its not working source = wc.DownloadString(String.Format("http://" & cboHSearch & "/cse?cx=013269018370076798483:gg7jrrhpsy4&cof=FORID:1&q=" + cboEngine.Text + "&sa=Search", Me.cboEngine.Text.Replace(" "c, "+"c), resultCounter))
For i = 1 To 60 Me.Controls("picturebox" & i).BackColor = Color.White Next
i want to change backcolor of picturebox but when i run program,i get this error :
An exception of type 'System.NullReferenceException' occurred in EZEE Restaurant.exe but was not handled in user code
Additional information: Object reference not set to an instance of an object.i go to Project->Add reference and then look for "System.NullReferenceException" but i don't find it.
following code from c# to visual basic, and I'm coming up with the following error: 'Public Event ItemCheck(sender As Object, e As System.Windows.Forms.ItemCheckEventArgs)' as an event, and cannot be called directly. Use a 'RaiseEvent' statement to raise an event.
Dim setting As My.MySettings lvl As Integer Dim xp As Integer Dim xpt As Integer
[code]....
I have done the settings as type integer and set the values that I wanted but I get this error: A first chance exception of type 'System.NullReferenceException' occurred in Click Game concepts.exe
im sure that this is incredibly simple but im very new to this. could someone tell me what Error 2 Operator '<=' is not defined for types 'System.Windows.Forms.TextBox' and 'Integer'. K:programmingchapter 4 labchapter 4 labchapter 4 labForm1.vb 16 24 chapter 4 lab
I'm upgrading a project from VB6 to VB2008.I have a routine that clears a combo box, named 'cmbDataTable' which could be on any form. I pass the form and the combo box is cleared.
[code]...
I assumed it would be the same in VB2008 but I get the error.'cmbDataTable' is not a menber of 'System.Windows.Forms.Form'I am working my way through the project, first updating the global procedures - this is one - I haven't written the calls so cmbDataTable doesn't yet exist.
THis is my error: The designer cannot process the code at line 25: Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font The code within the method 'InitializeComponent' is generated by the designer and should not be manually modified. Please remove any changes and try opening the designer again.
Callstack is: at Microsoft.VisualStudio.Design.Serialization.CodeDom.XML.CodeDomXmlProcessor.CreateQuoteExpression(XmlElementData xmlElement) at Microsoft.VisualStudio.Design.Serialization.CodeDom.XML.CodeDomXmlProcessor.XmlElementData.get_CodeDomElement()
