Answered DataRow System.NullReferenceException
Oct 13, 2010
I have a MyDataGridView.DataSource = MyDataSet.Table(0) and the AllowUserToAddRows = True Once the user have finished typing in the column zero I have to check if they didn't type invalid stuff. It have to be numeric and 4 chars long.
the code is:
Private Sub Result_CellEndEdit(ByVal sender As System.Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles Result.CellEndEdit
If e.ColumnIndex = 0 Then
[code]....
And it is not all the time, but depending on how quick and stupid (i'm expecting stupid users, as usual) I click on the previous row or the AddNewRow row I get a the damn System.NullReferenceException on my If line:
If Not (IsNumeric(Result.Rows(e.RowIndex).Cells(0).Value) And Result.Rows(e.RowIndex).Cells(0).Value.ToString.Length = 4) Then I'm really not in the mood of just put a Try Catch, as it looks like bad programming in this case. I've already tried a couple variations with "is nothing" but no success?How could test it won't cause a Null exception before testing the row value?
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Apr 4, 2012
Here is the stack trace:
2012-03-16 19:15:09Z E System.NullReferenceException: Object reference not set to an instance of an object.
at System.Timers.Timer.set_Enabled(Boolean value)
at System.Timers.Timer.Stop()
Here's the code:
Timer declared as private member variable.
Private _myTimer As System.Timers.Timer
Initialize timer method.
[code]....
The timer has to have a value or else the Timer.Stop() call would be throwing the exception. This is a sporadic error and I'm just trying to see if anyone has experienced this before or if anyone has any ideas of what could be causing it. It is occuring in a WinForms application in the event handler for the Elapsed event of the Timer, but it is only occuring sporadically on the users computer. I haven't been able to reproduce the error myself.
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Feb 24, 2010
I've got a little problem here:
Code:
Dim DirInfo As IO.DirectoryInfo = Nothing
... some code ...
Me.Tag = DirInfo.FullName
In this code, DirInfo.FullName is sometimes null. So I put this code inside a Try Catch. Although it works fine but I see a System.NullReferenceException in Immediate Windows. I just want to prevent it.
So tried:
If DirInfo.FullName IsNot Nothing Then Me.Tag = DirInfo.FullName
If DirInfo.FullName <> Nothing Then Me.Tag = DirInfo.FullName
If DirInfo.FullName <> "" Then Me.Tag = DirInfo.FullName
But I still get this System.NullReferenceException! How should I check DirInfo.FullName so I prevent this exception?
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Nov 25, 2009
Function GetHtml(ByVal url As String, ByRef web As WebBrowser) As String
Dim WebString As String
Dim myURI As New Uri(url)
web.Url = myURI
WebString = web.Document.Body.InnerHtml
Return WebString
End Function
System.NullReferenceException
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Jun 22, 2011
System.NullReferenceException was unhandled
Message=Object reference not set to an instance of an object.
Source=Image Invoice Management
[Code]......
i do understand that the list count is 0 so shouldn't it be declairing Start_Pos = 0
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Jan 23, 2012
i have a code that grabs an image from a site, this works fine and it does get the image fine, but every now and again my internet runs slow and it takes a while for the image to pop up thus causing the error:[code]How would i make it display the msgbox if it returns NullReferenceException error ?
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Sep 27, 2011
i have a small problem with my code that only happens every now and again.Im using multi threading on this and every now and again i get this error: System.NullReferenceException was unhandled Message="Object reference not set to an instance of an object."
Some times the program completes perfect with no errors and sometimes i get the above error.When i get the error there is always 1 item left in the list but when it completes perfect no items are left.Again this error does not appear every time, only every now and again. For example i had to run my program like 20 time to get this error, 19 times it worked perfect with no errors and 1 time with this error.
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Feb 9, 2011
This is my first ever post in this wonderful forum. I am new to vb.net programming. Given below is a piece of code which throws a system null reference exception at the end of the loop. I am unable to figure out the problem. "drledger" is null at the end of the loop. Even though i am able to catch the exception what can be done to avoid the null reference exception.
Private Sub btnSalesExport_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSalesExport.Click
Dim iRowMax As Integer
[code]......
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Feb 15, 2012
i have this code in my btnsave..it can detect conflicts but after that a dialog box saying: An unhandled exception of type 'System.NullReferenceException' occurred in AppointmentSchedulingClient.exe
Additional information: Object reference not set to an instance of an object. and it points to the green one below.
If Val(cbostart.Text) > Val(cboend.Text) Or Val(cbostart.Text) = Val(cboend.Text) Then
MsgBox("Error in time.", MsgBoxStyle.Information, "MESSAGE")
[Code].....
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Jul 1, 2009
I have a program that will print dwg and idw drawings to different printers. from our drawing vault we kan use a plotbutton which creates a pcf-file (text file) and copies the drawing to a specific location. the program reads the pcf file which contains the max printsize for the drawing, who is printing it, nr of copies, location of the drawing. all data is written to or read from a small database. as long as there are drawings the printing goes fine, they are listed in a datagridview on the form. As soon as the last record is removed from the datagridview I get the following error[code]...
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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)
[code]....
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Jan 20, 2011
im wondering which way may be better to find out the number of cols for a row:
1) row.Table.Columns then count
2) row.ItemArray then count
3) am i missing something, is there a much more "direct" way to do it?
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Aug 14, 2009
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
[code]....
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Mar 5, 2009
I've been trying to highlight a search result in DataTable. First, I loop through rows of DataTable and call a function to look for a matched keyword to highlight those words, then update DataTable row with a new string with highlighted keywords.I bind the DataTable dtResult to the DataList. It worked fine until I added this code block to SearchDemo function to highlight the keyword :
For i = 0 To dtResult.Rows.Count - 1 Step 1
Dim strTemp As String = dtResult.Rows(i).ToString
strVerse = blHelper.Highlight(s, strTemp)
[code].....
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May 24, 2011
I am in great trouble, I have a project on visual studio 2008 and I getting connectionstring using ConfigurationManager.ConnectionStrings("connestionstring") .ConnectionString. this project have a app.config file which contain
[code]...
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Apr 26, 2010
I get this message each time I run the appA first chance exception of type 'System.NullReferenceException' occurred in <Applicaton>I have isolated the key Subs which seem to upset it, but I cannot for the life of me figure out what it is about it that's upsetting it. I have used On Error Goto etc for the time being, which gets around it but I would like to solve it rather than jumpver it.Err.Description returns "Object reference not set to an instance of an object."My sub looks like this:
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Jan 25, 2011
I am able to query/read the event log using VB.NET 2005 (Win XP). But still I have a problem reading the "Message" / "description" of the event log.I am getting a System.NullReferenceException while reading the "Message" / "Description" of the event log.Also when I use System.Diagnostics.EventLog and read all the Event on by one I am able to read the message/description of the event. This is the code:
Public Sub ReadEvent()
Dim iCount As Int16
Dim PastFourHours As Date = Date.Now.AddHours(-4)[code]......
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Jan 18, 2010
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.
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Aug 5, 2010
I'm converting another project from VS2003 to VS2010 and am getting this message in the Immediate Window before I hit my MyBase.Load. From the warning, it looks like somting is undefined yet is being used - causing an exception. How can I trace this down?My app uses 2 DLLs, could the msg be coming from them during their load?
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Nov 29, 2011
Here are parts of my
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
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Oct 16, 2011
I am trying to start the process with the following parameters When I try to start it though I get an System.nullreferenceexception: Object reference not set to an instance of an object
Dim exepath As String = Application.StartupPath + "inffmpeg.exe"
Dim sr As StreamReader
Dim cmd As String = " -i """ + input + """ -ar 22050 -y """ + output + """"
Dim ffmpegOutput As String
[code]....
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Jan 12, 2010
i am using VB.net 2003 and i am trying to get the number of rows of a dataset from form1 into form2 in order to use it for something else and i am getting the error"System.NullReferenceException occured...Additional information: object reference not set to an instance of an object"...my code is like this:in form1:Public x as integer= me.dataset.table.rows.count here it gives me the error
in form2:
dim frm as new form1
msgbox(frm.x)
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Oct 23, 2009
I have recently gotten my hands on a free, open-source IMAP connection API.So far, I have been successful in creating a connection to one of my accounts.Where I'm getting stuck is retrieving folders and/or emails from those folders.Does there happen to be anyone here that is familiar with this API, or even Gmail (particularly the folder structure for IMAP)?
If not, here is a link to the DLL that is listed on sourceforge and the company's website that created it (if you feel like testing):
Koolwired
Sourceforge - Koolwired API
I have created a test account so feel free to use the code below without worrying about username/password issues; I'll just delete it when I'm done with it.Here is the code I have made so far for making a connection:
Dim gSession As New Koolwired.Imap.ImapConnect("imap.gmail.com", 993, True)
Dim gAuthenticate As New Koolwired.Imap.ImapAuthenticate(gSession, "imap_test@serysoft.com", "imap_test")
Try
[code]....
When I run that code, I get an error that states:System.NullReferenceException: Object reference not sent to an instance of an object. (The bold line in the above code).
Now, I'm not sure exactly what that means. Does that mean it tried to access the server and "INBOX" doesn't exist so it gets returned a NULL value? Or is it possibly the coding itself?Maybe the Gmail folder system is weird due to the fact they use labels (even though from what I have read online, the labels act as the folders in the IMAP system).
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Jan 27, 2011
I'm getting System.NullReferenceException error when I try to add the employee info to the Employees list.
[Code]...
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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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Oct 30, 2011
I am completely new to ASP.NET and VB as well as C#. I am trying to add customers to a contact list out of a DB. Then the list can be referenced to call them up. But when I try to run it I get System.NullReferenceException: Object reference not set to an instance of an object. In line 19.
Here is my code:Page 1 is default page...it connects to the database and grabs the contact information and allows me to select the current contact and add them to a listbox on a separate page:
Imports System.Data
Partial Class _Default
Inherits System.Web.UI.Page
[code]....
The error occurs on line 19 (For Each customerEntry As DictionaryEntry In Customer) in the second set of code from the default2 class.
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Aug 12, 2011
I am coding in vb.net. At times the data is empty/null this is due to user's input into the db.i will like to bypass it, however i get no luck.here is snippet of my code:
If hct.mydbvalue.name IsNot Nothing Then
dr("mydbvalue") = hct.mydbvalue.name
End If
I still get an error: System.NullReferenceException: Object reference not set to an instance of an object.is there a way if it is a null value to not do anything?
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Apr 26, 2011
look after the error i'm having.
module1.vb
Imports System.Data.SqlClient
Module dbconn
[code]....
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Feb 18, 2010
This is my code:
Public UserBookings() As String
If dr.Read() Then
Dim intCounter As Integer
[code]....
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Jan 2, 2010
I have a custom class that all my pages inherit from
Public Class Page : Inherits Page
Private Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
'Display Admin Controls (Buttons) '
If User.Identity.IsAuthenticated Then
[code]....
But for some reason I'm getting this error:
System.NullReferenceException: Object reference not set to an instance of an object.
on this line
If User.Identity.IsAuthenticated Then
This only started happening in IIS7. I have been using this application in IIS6 for over a year without issue, and it's only since I migrated to IIS7 yesterday that this exception started.
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