VS 2010 Webbrowser Access Violation Exception
Apr 26, 2012
I have exactly same problem as guy at [URL] . Quote: I'm using multithread in my application. in each thread, launch a form which has a webbrowser. each browser is controlled by another thread to test some sites. however, sometimes, it has some access violation exception. these exceptions are not beause of cross thread issue since all processing for the browser are using delegate. And the problem is: I can not catch the access violation exception.
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Sep 8, 2010
win7 64bit, VB express 2010.
I'm working on a project. The main form is a MDI parent, it host a control form. on control form, there is a button. when click it, it will start, say 10, threads.
each thread will open a standard alone form (not mdi). on each form, it has a web browser control. when the form opened, it will start a new thread which makes the web browser control load a url, then depends on the links in that url, it will load another url, and loop for some times. then, the thread stops, and the form closes.
for some reasons, I got this weird exception:
AccessViolationException was unhandled by user code. Attempted to read or write protected memory. This is often an indication that other memory is corrupted.
1) the exception happens randomly, and not always happen. when it happens, it is always some code related with the web browser, i.e.
Not (MDIWebBrowser.ReadyState = WebBrowserReadyState.Complete)
or
MDIWebBrowser.Document.Body.InnerText()
2) I put a try catch in, but, it can not catch this exception. If I just close the exception dialog, sometimes, it keeps running without problems. sometimes, it just pauses the webbrowser control.
so, I did some research. it seems many people had the exact same problem. and it seems the best choice is:
[URL]
I checked all solutions suggested, even manually change the DEP, by using "bcdedit.exe /set {current} nx AlwaysOff"
but, the exception still pops up.
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Jul 5, 2010
I'm been upgrading an application form VB6 to VB2008
I've started getting "Access Violation Exception was unhanded - Attempted to read or write protected memory" error message.
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Jan 20, 2010
i have get that exception when save my db with TableManager.UpdateAll command:
Violation of UNIQUE KEY constraint 'IX_InstalmentID_DueDate'. Cannot insert duplicate key in object 'dbo.Instalments'.
This error only occurs if I remove existing records from BindingSource (without saving) and add them again (with same date) and then save the all changes with UpdateAll command. Here is the my table schema:
Instalments
DebtID (PK)
InstalmentID (UK - Unique Key combine* )
[code]....
I have created a unique key combining InstalmentID and DueDate fields. Instalments tables is a child table. Its parent table is Debts.
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Mar 1, 2012
I'm trying to call a Dll function which looks like this (in the C/C++ Dll):declspec(dllexport) void execute(char** ReturnMsg, char* serverAddress, char* commandLine)
The VB 'wrapper' function looks like:
<DllImport("TPClient.dll", EntryPoint:="execute", CallingConvention:=CallingConvention.Cdecl, CharSet:=CharSet.Auto, ExactSpelling:=True)> _
Public Shared Sub tg_execute(<Out()> <MarshalAs(UnmanagedType.LPStr)> ByRef returnString As System.Text.StringBuilder, _
[Code]...
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Apr 25, 2012
I put a try/catch block around a bit of code that occasionaly throws an expected exception, but rather than catching it and displaying the message box, it stops the debugger and alerts me that the exception is unhandled.How do I handle this exception so my code doesn't stop when the exception occurs?
Friend myDevInfo As New devInfo
''' <summary>
''' Closes the device handle obtained with CreateFile and frees resources.
[code]....
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Apr 8, 2009
Im having a access violation error on my QueryPerformanceCounter Statement and im not sure why. I've search the internet for answers but found none.Declaration:
Private Declare Function QueryPerformanceFrequency Lib "kernel32" Alias "QueryPerformanceFrequency" (ByVal lpFrequency As Int64) As Boolean
Private Declare Function QueryPerformanceCounter Lib "kernel32" Alias
[code].....
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Apr 23, 2010
I am using VS2010 release edition with Windows XP, Vista, 7
my programme works fine in XP but fails in Vista and 7.
All I am trying to do is open a OpenFileDialog to get a filename. [code]...
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Oct 1, 2011
I have a single user app that I wrote and have been using for more than a year that uses an Access 2003 database. Today, out of the blue, I started getting a DB concurrency violation whenever I tried to update one particular table in the database. After trying to troubleshoot what the problem might be, I just deleted that table and recreated it and the problem went away.
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Dec 15, 2011
I'm having an issue with a concurrency violation when I save my data(only on one form). All other data forms are working fine. This form has a lot of code, so to isolate the problem I added a new form to the project and dragged the table from my datasource, in detail, to the form. this is the only code in the form,
[Code]....
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Oct 26, 2010
When my project starts, it first checks for the existence of certain rows in the database. During testing, I often delete these rows, as they get kind of messed up over time due to all the odd tests I am running. For that reason, if when the project starts, if the records are not there, the program first creates them.The records are pretty static over the lifetime of the project, so they are held in a dataset for ready access from various parts of the program. Therefore, if the records are not in the database, the records are added to the dataset, and the dataset is updated back to the database. This works without any issues.However, one of the easiest actions to take will cause one of these records to change two fields, and a new record will be added. Those are all the changes that are caused by this action. Those changes are then updated to the database...or so I hoped, but when I try that I get an exception stating:[code]I have looked at the datatable that is being updated, and there are, as I expect, two records being changed. One of the records is the new one that is being added, while the second record is the record that was changed. I have noted that the change is, in fact, different from what is in the database, so this really IS an update.
However, I also noted that if I then stop the program and start it again, all is well. This indicated to me that it was actually the routine that created the records that was causing the trouble. Therefore, to test this out, I tried a totally horrible solution. I altered the method that writes to the new records to the database so that after it wrote each record, it would clear the whole dataset and fill it all again. That's obviously a terrible thing to do, but it works. If I write each record, throw out the dataset and re-create it, then I don't get any exceptions when I later try to modify it.This makes no sense to me. What am I doing in that first method that could be putting the Dataset into a state where it fails on any further modifications? I should add that the code that actually pushes the changes to the dataset down to the DB is the same for both methods. In fact, the database is updated in an UpdateDB method that is called from that first method (which creates the initial records if they are missing), as well as being called by the other methods that alter the dataset. I have also confirmed that ANY alterations I want, whether they add, remove, or just alter records, works fine. It is only that one method that creates the initial records that is causing me trouble. Moreover, it is not the actual update of the DB that is doing it, since that same method works fine ever after. Further testing has showed that the issue is row by row. As each initial row is added, it can't be modified by any other code until the dataset has been re-read from the DB. url...
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Mar 31, 2011
i have this delete code
My search
Public Sub mnamesearchdata()
'search data
Dim blnfound As Boolean
blnfound = False
[code]....
My Database In case. Having weird issues also were my database will be wiped out. Having 0 record.
[URL]
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Apr 18, 2012
I was scripting a very basic process manager, with a ListView component, and it was working fine for many days, up until now.Here is the code for getting processes:
Dim Process As New Process()
Dim Count As Integer = 0
ListView1.Items.Clear()[code].....
The line of code where I put "*WIN32 EXCEPTION LINE* keeps running into an error(Win32 Exception was unhandled; Access is denied). Here is the full error description:
System.ComponentModel.Win32Exception was unhandled
ErrorCode=-2147467259
Message=Access is denied[code]....
As I said before, this had been working for several days, up until now.
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Jul 4, 2010
I am getting a "null reference exception" error when I run my application, this error occurs even before the webbrowser has navigated anywhere. Why would I get this error without a webbrowser document complete occurring?
vb
Dim HTML As String = WebBrowser2.Document.Body.InnerHtml.ToString
If HTML.Contains("Submit Comment") Then EnterData() Else NextURL()
End If
I don't understand why I would get this error when I haven't even navigated anywhere? Forgot to say that this code is inside WebBrowser2 document_complete.
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May 6, 2011
I want to make a webbrowser, but only have it show one specific thing and not the whole page. The thing I want it to show and only show is in about the middle. How would I frame the page, and put it on the webbrowser?
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May 8, 2009
It is possible to catch an exception and throw a new exception which wraps the first exception as an inner exception: [URL] Also, if I call a function and it throws a certain error, but I catch it, will the calling code's catch handler execute? If so, and it is of a higher exception type, is this not wrapping the exception? eg I can throw exception ex of type IndexOutOfRange, log it but rethrow, catch a higher up exception and do something, or I can throw a new exception and wrap an inner exception like:
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Oct 8, 2010
The exception:
"Input string was not in a correct format."
Appears when I try to access a field on my page like this:
.TransmissionId = IIf(FormValues("TransmissionId").Length > 0, Integer.Parse(FormValues("TransmissionId")), 0)
However it works for another field which is the same exact type of field, accessed like this:
.StateId = IIf(FormValues("StateId").Length > 0, Integer.Parse(FormValues("StateId")), 0)
Where could the mismatch and exception be coming from? What could be the fault? The field doesn't have a value when I'm pulling it. Do I have to test for a value different for this number field than I would have to for a text field?
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Mar 23, 2010
I'm getting the error below for this SQL statement in VB.Net 'Fill in the datagrid with the info needed from the accdb file
[Code]...
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Jan 10, 2010
Ive created a simple application that works fine when i debug and test it though visual studio but when i deploy the application, download it and install it onto my machine i get an error.basically when the first form loads it checks for a file called "New Folder" in my program files folder on my machine if the file is not there, then it adds the file. the code im using to do this is:
If System.IO.Directory.Exists(My.Computer.FileSystem.SpecialDirectories.ProgramFiles & "New Folder") Then
Exit Sub()
[code]....
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Sep 30, 2010
I've seen other people that have had this exception post on the forums, but none have had it happen like my situation. So I have a multi-threaded VB.net app that will have the protected memory exception occur while it's in the Thread.Sleep call.
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Oct 30, 2010
I am just writing a simple file browser. It works without problems when I point to a specific directory but throws "UnauthorizedAccessException access to the path .... is denied" when I point to drive "C:\" or "D:\".
If Not txtToSearch.Text = Nothing Then
ListBox1.Items.Clear()
FC = 0
For Each foundfile As String In My.Computer.FileSystem.GetFiles("D:\", FileIO.SearchOption.SearchAllSubDirectories, Nothing)
Dim title As String = My.Computer.FileSystem.GetFileInfo(foundfile).Name
If title.Contains(txtToSearch.Text) Then
ListBox1.Items.Add(title)
FC += 1
End If
Next
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Jan 17, 2011
I am trying to get a list of files using this line of Dim files() As String = IO.Directory.GetFiles("D:", "*.*", SearchOption.AllDirectories)But it errors out on folders that are inaccessible, like the RecycleBin folder & the program stops. So how do I get a list of files in all folders, while skipping the inaccessible one
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Apr 24, 2010
I am making a simple program that allows a user to add and delete contacts from a database. Whenever I try to delete a contact that was created in a previous session (by session, I mean time that I ran and then ended the program), it is fine, but when I try to delete a contact created in the same session, it says: "Concurrency violation: the DeleteCommand affected 0 of the expected 1 records." here is the code for the delete button: [code] I noticed that, since the error does not happen on a new session, that if I added the code that happens at the form_load, I could fix the issue.
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May 11, 2009
running my app in Debug Mode within Visual Studio I've been able to allow the user to Open an Access Report and if need be print it off. This has worked great.Unfortunately when I run the .exe file I get the following Unhandled exception message.'Could not load file or assembly 'Interop.Access, Version=9.0.0.0, Culture=neutral, PublicKeyToken=nuill' or one of its dependencies. The system cannot find the file specified.'Like I say above, this works when run from within Visual Studio, the code as far as I know is not the problem.
Here's the code I use on a menu item click,
Dim strFileName As String
Dim str As String
Dim RepName As String
[code]....
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Apr 10, 2010
I tired this [code]...
but this code not working on windows vista, i can use it on windows xp, i think problem is user permissions but i have to delete or create file via my application how can resolve this problem.
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Mar 30, 2009
I want my program to be able to edit a values within a registry key that resides in 'HKEY_LOCAL_MACHINE'
My.Computer.Registry.SetValue("HKEY_LOCAL_MACHINESOFTWAREXYZ", "MyValue", "MyData")
The above works fine in Windows XP, but throws an UnauthorizedAccessException in Vista.
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Aug 4, 2010
I am creating a file and then trying to read and write to it. I'm coming up with an UnauthorizedAccessException wa unhandled. My question is, How do I get around this properly or otherwise improperly to read and write to my text file?
Imports Scripting
Imports System.IO
Imports System.Security
Imports System.Security.Permissions
Public Class Form1
[Code] .....
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Nov 19, 2009
I get this:
Cannot access a disposed object.
Object name: 'MainForm'.
Here is the code I'm running. It's after the MsgBox "Readme file cannot be found. Please put the original readme in the current working directory of this executable." (and it's dismissed) that I get the unhandled exception error.
Private Sub MainForm_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim readme As String = My.Computer.FileSystem.CurrentDirectory + "
eadme_ctb_v100.txt"
MsgBox(readme)
If My.Computer.FileSystem.FileExists(readme) = True Then
[Code] .....
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Mar 14, 2010
I would like to build a base class for my SQL Data Access Layer. I have most of it based out, but have a question about how to handle errors within the base class. I have a method for ExecuteNonQuery, ExecuteReader, ect...
[Code]...
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Dec 21, 2010
I'm attempting to insert rows form a ListView into an access DB. Here is the code from the Finish button. From line 55 down is my trouble area.
[Code]...
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