System.AccessViolationException While In Loop
Jun 16, 2010
Here is a part of my code which loops through the items in a checkedlistbox.. The text of each item is the name of a computer.When the loop runs for the first time, it runs fine, but when it goes through the loop the second time I am getting the following exception:Attempted to read or write protected memory. This is often an indication that other memory is corrupt..The code connects to wmi and retrieves the time zone information from the registry.. It is given below: [code]' then there are lines of code which does something with 'lngTZBias..So, if the checkedlistbox has only one item checked, the code runs fine.
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Oct 20, 2010
Win7 64 bit; fully patched VS2008 targeting FW2.0; VB.Net; running in Debug Mode (not tested in Release mode)I have a resonably complex app which I am refactoring a bit. As part of that, I relocated some code from a subroutine into a Click Event Handler. The Event Handler will, late in the handler, call the, reduced in function, subroutine. The point of this is thatNow when I click the button associated with the modified Handler I get:A first chance exception of type 'System.AccessViolationException' occurred in System.Windows.Forms.dll<br />With Error System.AccessViolationException Attempted to read or write protected memory.This is often an indication that other memory is corrupt.
at MusicManager2009.frmMain2.cmdLoadAlbum_Click(Object sender, EventArgs e)
at System.Windows.Forms.Control.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnClick(EventArgs e)
[code].....
All functions of the app, except those that start from the buttonclick in question, work as before in the problem version.The problem persists after rebuilding the entire solution, after restarting VS, and after rebooting the PC.
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Oct 8, 2009
I am using a com DLL in the following manner:
#Region "API Function"
<DllImportAttribute("abc.dll", EntryPoint:="optcntl")> _
Public Shared Function optcntl(ByRef pBlocks As blocks) As Integer
End Function
#End Region
This DLL using the other four dlls to complete its processing. If I change the current directory path from the /bin/ folder to other folder in C or D drive which contains all the DLL. I get the following Error message: System.AccessViolationException: Atempted to read or write protected memory. This is often an indication that other memory is corrupt
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Sep 21, 2006
I seem to be in a quandry over an error that makes no sense to me.In following some examples I have found on the Net, I've been attempting to use the MSHTML library in vb.net to access the HTML DOM.[URL]...when I look at the error message, it tells me that memory could be corrupt elsewhere. I've attempted this line of code by omitting the "http://"portion of the URL, byt trying numerous web sites, and with various other arguments in the 2nd parameter, such as "", ControlChars.NullChar and "null". I've also reset my PC and created a brand new application with only that code and get the same results.I am using VS.NET 2005,version 8.0.50727.42I don't know if it will help, but the details from the exception object are as follows:System.AccessViolationException was caught Message="Attempted to read or write protected memory. This is often an indication that other memory is corrupt." Source="mscorlib" StackTrace: at System.RuntimeType.ForwardCallToInvokeMember(String memberName, BindingFlags flags, Object target, Int32[] aWrapperTypes, MessageData& msgData) at mshtml.HTMLDocumentClass.createDocumentFromUrl(String bstrUrl, String bstrOptions)at MSHTML_DOM_Practice_1.Form1.createDoc(String URL) in D:Dev V.2Misc practice projectsMSHTML DOM Practice 1MSHTML DOM Practice 1Form1.vb:line 19I,
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Sep 18, 2009
I have a website that i've been working on for about a year now.Recently, it's started throwing System.AccessViolationException every now and then, in my dev machine, mostly, when I was away from the machine.I haven't changed anything on the server code in weeks, since I've been working 100% on the Javascript part, and this error started appearing recently.
Also, the code I'm doing is 100% managed. I'm not doing any interop, calling strange DLLs, nothing. It's pure VB.Net, so I don't see how I could be generating one of these myself.Now, I've been using this new machine for a couple of months, and it's not working 100% right. Every 2 or 3 days I'm getting a blue screen for example. I haven't had time to diagnose it properly, but I'm suspecting I may have a faulty RAM chip.
[Code]...
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Apr 1, 2011
I am trying to find the time-outs the user has set for the PC similar in function to the command line:
powercfg /q SCHEME_CURRENT SUB_SLEEP but I want to do something a bit more elegant than firing off a command and parsing the values out of the captured output. I've managed to source a number of element examples from the net and cobble parts together into a program.
I've got a fair way but am now stuck on the call to powrprof.dll - PowerEnumerate function. I've checked it on Microsoft's site and my call seems to be okay yet it still fails with 'System.AccessViolationException was unhandled'
[Code]...
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Jul 25, 2009
I always get this error during the Paint event: System.AccessViolationException was unhandled. The weird thing is that it doesn't happen the first time it goes through.
Here's the code.
Friend CustomFont As Font = GetCustomFont()
Private Function GetCustomFont() As Drawing.Font
Try
Dim PFC As Drawing.Text.PrivateFontCollection
[CODE]...
Symbols is just a 2 dimensional array of characters.
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Aug 20, 2009
I receive random AccessViolationException on client machines. I have captured the exception text and have pasted it below. Unfortunately this error is not happening on code that I have written it appears to be happening when the .NET is trying to draw a group box on the form. System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.at System.Drawing.SafeNativeMethods.Gdip.GdipDrawLineI(HandleRef graphics, HandleRef pen, Int32 x1, Int32 y1, Int32 x2, Int32 y2)at System.Drawing.Graphics.DrawLine(Pen pen, Int32 x1, Int32 y1, Int32 x2, Int32 y2)
[Code]...
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Aug 16, 2010
I get AccesViolationException with a code when I try to send a packet back to a server. I tried another way with my packet sniffer dll, there I get a SEHexception.Here is my code I used where I get the AccesViolationException:
Public Declare Auto Function vpSendPacket Lib "VBPCAP.DLL" (ByRef packet() As Byte) As System.Int32
Public Sub sendpacket()
Dim str As Object[code]....
I think the program I'm trying to send to is protected.
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Mar 18, 2011
I bumped onto another little problem during my project,the problem is as following:I have a project with multiple forms. My startup form is Form1.On Form2 I have a button that calls the open file dialogue (ofd)When I try to open it I get a " AccessViolationException *Attempted to read or write protected memory. This is often an indication that other memory is corrupt.*Now the strange thing is that,when I place a button for the ofd on my form1 ( my startup form ) the dialogue does open and it doesn't crash.If I after first opening the ofd on form1 continue to form2 the ofd works there aswell.I've been tracing this problem down as good as I can and I found out that the ofd doesn't work anymore after I read data from a DB ( access )
To show you what I mean I'll type the code I used for the DB reading here:
[Code]...
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Aug 5, 2011
i want an application that has no forms but a tray icon... i do not want to add a form to do this or have a loop..[code]I have been programming in VB for years.
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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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Dec 15, 2010
I wrote a backup utility that synchronizes a list of folders. Errors appear in a list. In the list I can right-click to retry, exclude the folder next time, or open the folder in explorer to examine.When I shell to explorer I get an AccessViolationException. Form1 opens Form4 with Form4. ShowDialog(), and that's where the error occurs. The error does not occur within Form4 where the shell function is called. memory must be getting trashed somehow.I've used two methods, Shell and System.Diagnostics.Process.Start. Each produces similar results. Shell waits awhile before causing the error, but Process.Start causes the error immediately.This is VB.Net 2010 using framework 4, though I did resolve a shell problem once before with VBA by writing out a VBScript file then shelling to the VBScript file.
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Dec 15, 2010
I wrote a backup utility that synchronizes a list of folders. Errors appear in a list. In the list I can right-click to retry, exclude the folder next time, or open the folder in explorer to examine.
When I shell to explorer I get an AccessViolationException. Form1 opens Form4 with Form4.ShowDialog(), and that's where the error occurs. The error does not occur within Form4 where the shell function is called. Memory must be getting trashed somehow.I've used two methods, Shell and System.Diagnostics.Process.Start. Each produces similar results. Shell waits awhile before causing the error, but Process.Start causes the error immediately.
This is VB.Net 2010 using framework 4, though I did resolve a shell problem once before with VBA by writing out a VBScript file then shelling to the VBScript file. I don't think the process being started is isolated enough. It's sharing memory or something else.
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Apr 9, 2011
I have a simple loop that "sleeps" a thread..Out of nowhere i will get this error below, it could be 1 minute, 20 seconds, 5 seconds, all at random times...how to fix it?
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Sep 6, 2010
Looking for something like:
dim rect as system.drawing.rectangle
For each point in rect
Debug.print(point.name, point.value)
Next
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Dec 28, 2011
The error message that I've been getting for the past few months when trying to access functions of a specific third-party .dll using vb.net is this: "An unhandled exception of type 'System.AccessViolationException' occurred in test.exe Additional information: Attempted to read or write protected memory. This is often an indication that other memory is corrupt."
I've been researching this error message, and I have come to know that it is likely due to either attempting to access memory that isn't available or due to "enhanced" security features.I am trying to access a third party .dll. The functions in that .dll all deal in one way or another with Handle types (either returning them or accepting them as parameters). I understand that handle's can be essentially pointers to pointers (pointing to an entry in a memory table, which is itself a pointer), and I also understand that handle's don't, strictly speaking, exist in the .NET framework, but I do understand that through some combination of IntPtr's and possibly the Marshal class, they can be dealt with.
I don't believe vb.net's lack of a Handle type is the problem, because the dll function that I am calling, which on success returns a handle, returns a number <= 0 if the ip address it is searching for is not found, and the ip I specified doesn't exist. Also, the error really only occurs when executing the code from within the the Visual Studio environment. I compiled the executable and ran it 77 times(literally), and I only got the error on the 77th try.
I'm trying to find out all I can about this error. I would like to completely eliminate it. Could the error come as a result of something happening within the dll itself? The function asks for an ip address, and the ip address I have specified doesn't currently exist on the network, but as far as I know, the function handles that by returning a number less than or equal to zero. I am very confused as to what the problem could be. I have successfully interfaced with .dll's before. I've read about the hotfix for .NET 2.0 regarding this error message,but I'm a little skeptical. I've tried everything else I can think of, though, so I may give that a shot.I'm 100% certain that:
-I am calling the correct function within the .dll
-I am using a signature that matches the signature of the function
-The error has nothing to do with User Account Control.
The code is very simple to try to isolate the issue:
Imports System.Runtime.InteropServices
Module test
<DllImport("3rdparty.dll", EntryPoint:="#12")>[code]......
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May 27, 2010
I have a subroutine that was written in fortran that I need to call from VB.NET where all of my other functions are written. I did not write the fortran, and hardly know fortran. I am getting the below exception on my dll function call and don't know how to fix it. I wonder if it is due to incongruent variable lengths? I have the source for my fortran and compiled it using the g95 compiler. I have tried compiling it with a flag on which is supposed to force all of the reals to 32 bits (-r4). It weirds me out that you don't seem to be required to initialize variables before use in fortran. I thought it was supposed to be a ridged language.
[Code]...
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Oct 6, 2011
I'm trying to call a C++-compiled DLL from VB.net and I'm running into some problems. Seems like there's an obvious solution, but I can't figure it out.Here is the function declaration in C++:
MyFunction(int trailingaveragesize, double sigmasize, int myflag, int sizeSeries, double *Xdata, double *Ydata, int sizeinputparameter, int *averagePairs, double *PositionsSize, double *PnLSize)
Here is how I'm calling it in VB.Net:
[Code]...
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Dec 24, 2010
I get an AccessViolationException using this code (attempted to access protected memory, this is often an indication that other memory is corrupt) on the line in DoWaitNotify that copies the pixel data back to the location in memory. In my experience, that usually means that the array is too large, but it all seems to check out. Does image data expire after a certain time or something?
Public Class Form1
Private Const NUM_THREADS As Integer = 3
Private Original As Bitmap
[Code]....
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Jan 11, 2010
VS 2010 [RESOLVED] Marshal.ReadInt32 -> AccessViolationException
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Mar 2, 2011
We recently upgraded VS 2005 to VS2010 and converted an application seemingly without any problems. But when deployed to the customer they are getting intermittent errors at seemingly random places in the program which force the application to close and AccessViolationExceptions being logged to the Application Event Log.
The customer's site is a multi user environment with the application hosted on a server and users running the app via RDP. We get two errors in the event log:
Application: ContainerDepotSystem.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.AccessViolationException
Stack:
[Code]...
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Jun 25, 2010
im trying to select some rows based on a criteria, i was wondering is it faster if i create a dataview (based on the criteria) and then loop through the view? or should i loop through the entire datatable and check the criteria manually.
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Aug 31, 2010
Private Declare Function CascadeWindowsNative Lib "user32" Alias "CascadeWindows" ( _
ByVal hwndParent As Long, _
ByVal wHow As Long, _
ByVal lpRect As Long, _
ByVal cKids As Long, _
ByVal lpkids As Long) As Integer
calling:CascadeWindowsNative(Nothing, &H4, 0, 0, 0)
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Mar 14, 2011
Makes the following statement about the code below:
**"The computer evaluates the loop condition in the Do...Loop statment to determine whether the loop instructions should be processed. In this case, the inputsales <> String.Empty condition compares the contenst of the input sales variable to the String.Empty value. As you know the String.Empty value represents a zero length, or empty, string if the inputsales variable is empty, the loop condition evaluates to True and the computer process the loop instructions. *If on the other hand the inputsales variable is not empty, the loop condition evaluates to false and the computer skips over the loop instructions.
Based on the code I think it is the opposite: ...that while the inputsales value is not empty it should evaluate to true and process the loop and if it is empty it should evaluate to false and skip the loop?
See below.
Option Explicit On
Option Strict On
Imports System.Globalization
[CODE]...
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Oct 2, 2010
I have a class library that uses the IApplicationAssociationRegistration Interface [URL]
Heres the code:
Class Library
IApplicationAssociationRegistration Class:
Imports System.Runtime.InteropServices
[code]....
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Mar 9, 2011
I know I am missing the obvious. I would like a label to show how many cycles in loop are left.
[Code]...
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Nov 23, 2011
I am constructing a program, i am new to Visual Basic, but i have past programming experience. I was wondering if anyone knew how to form a loop that could...lets say calculate the answer when two numbers are added together,and it would repeat this thousands of times, etc. And if there is a way, would it be possible to calculate the time taken to complete this loop.
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May 3, 2010
I have written a function that gets the alexa ranking of a given url, now this function works perfectly but I want to loop through a ListView of urls and grab the alexa rank of each item (url) with my function.The code works great if I put a MessageBox in the loop to test that the function is returning a value but when I remove the MessageBox the loop does not work.I need it to loop through adding each result without a MessageBox stop in each loop.
vb
For Each Item In ListView1.Items
Dim result As Integer
result = GetAlexaRank(Item.Text)
[code].....
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May 31, 2010
So I made a simple patform game where the player has to jump quickly while the platforms move to the bottom of the screen, as to not touch the bottom of the screen. But, I need to know how to create a loop to loop the locations of the platform. This means that after twenty or so platforms, the same platforms come up again, so that the player will have an "endless" game. I've declared all the platform's locations relative to the location of the first repeating platform:
[Code]...
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