Error : Attempted to read or write protected memory in c#

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Hi,
I am getting this error

Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

on this line of codes :-

DialogResult dr = openFileDialog1.ShowDialog();//error is here
          if (dr == DialogResult.OK)
          {
              label6.Text = openFileDialog1.SafeFileName;
              pictureBox1.BackgroundImage = Image.FromFile(openFileDialog1.FileName);
          }

I searched on google and find 100+ searched result and I read most of them, but I couldn't find proper solution on this.
I also change setting in VS2010 which is Option->Debugging -> unchecked "supress JIT optimization on module load(Managed Only)".
Still my error couldn't resolved ..

Please Help me to out..

Regards
Jayanta

Posted 10-May-14 3:32am

JayantaChatterjee

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emcp 10-May-14 9:39am

Does OpenFileDialog class work in an empty new project?

JayantaChatterjee 10-May-14 9:43am

Sorry I don't understand...

emcp 10-May-14 10:06am

OpenFileDialog is a built in class, and calling ShowDialog is throwing a memory exception. So making a new project and adding an OpenFileDialog, and calling ShowDialog, will rule out that anything is corrupted.

Otherwise, ensure you are not using a custom OpenFileDialog class.

Then check that the default folder, properties etc.. are not assigned to something that could throw an exception. However that would seem unlikely.

JayantaChatterjee 10-May-14 10:14am

OpenFileDialog is Build in Class(which .NET provide).
I checked OpenFileDialog in different project it worked fine.
The InitialDirectory property of OpenFileDialog is empty...

emcp 10-May-14 10:52am

try reinstanciate your dialog:
OpenFileDialog dlgOpen = new OpenFileDialog();
DialogResult dr = dlgOpen.ShowDialog();

emcp 10-May-14 11:09am

You shouldn't be getting this type of exception in managed memory.
So if that didn't work - then are you using any unmanaged objects that are being triggered (as OriginalGriff is indicating).

JayantaChatterjee 10-May-14 11:24am

I used only .NET classes(I think .NET is used Managed memory)..
How to find out unmanaged object in my Application??

emcp 10-May-14 12:28pm

You tried reinstanciating, as I said 2 comments back?
Yes .Net is managed, however you can use unmanaged blocks, dllimports, COM, DirectX...

JayantaChatterjee 10-May-14 12:33pm

I ReInstantiate the OpenFileDialog but its same error..:-(
I am not using any dll, Com or DirectX controls, only windows common controls...

emcp 10-May-14 12:36pm

try Message.ShowDialog("");

JayantaChatterjee 10-May-14 12:40pm

I tried Message.Show("") before the openFileDialog object creation , its okay(showing the message box), but after that OpenFileDialog.ShowDialog line gives same error.. :-(

emcp 10-May-14 12:45pm

try putting the OpenFileDialog in a try catch block.

JayantaChatterjee 10-May-14 9:47am

I have 3 Classes and 8 forms in my Project..
all project running good except this ... :-(

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OriginalGriff · Answer 1 · 2014-05-10T03:51:00

Solution 1

Start with the debugger: put a breakpoint on the ShowDialog line and run you app. when it reaches the line, the debugger will stop and wait for you. Look closely at the OpenFileDialog and make sure everything looks reasonable. Then look at the preceding lines of code and see if there is anything odd (or outside .NET) in that. If everything looks ok, single step execute the line and see what happens.

There is no simple "do this" fix for problems like this: as the error says, "This is often an indication that other memory is corrupt" - and that means trying to find out what, and where, and how before you can move on. So start by getting information, because you are going to need it!

Posted 10-May-14 3:51am

OriginalGriff

Comments

JayantaChatterjee 10-May-14 10:04am

this is the first line of button_click event in my project.
I also add break point to that line and debugging my project I found nothing suspicious , but same error occurred. :-(

OriginalGriff 10-May-14 10:11am

Then you need to look at what else you application is doing - because .NET doesn't normally throw exceptions on OpenFileDialogs (I use them all the time)

So look at what else your app is doing before you press the button - and if you can't spot anything start commenting out the form Load event, anything clever in the constructor, any timers, etc. (You can highlight it and use CTRL+K,C to comment a block of code, and CTRL+K,U to uncomment it).

When you have the error gone, start looking at teh code you removed, and put it back gradually.

JayantaChatterjee 10-May-14 10:21am

Thank You Sir..
I got the error generator code in my application, which is :
Data_Con Modi = new Data_Con();
if (paraVal != null)
{
Modi.SelectSta("select * from custDetails where custName='" + textBox1.Text + "'", "custDetails");
if (Modi.dataSet.Tables["custDetails"].Rows.Count > 0)
{
textBox2.Text = Modi.dataSet.Tables["custDetails"].Rows[0][2].ToString();
textBox3.Text = Modi.dataSet.Tables["custDetails"].Rows[0][3].ToString();
textBox4.Text = Modi.dataSet.Tables["custDetails"].Rows[0][4].ToString();
textBox5.Text = Modi.dataSet.Tables["custDetails"].Rows[0][0].ToString();
}
}
Modi.Dispose();
This code is in TextBox_leave event..
I create Dispose method in that class(Data_Con). close and dispose all the object in that class..
so now what i need to do??

OriginalGriff 10-May-14 10:27am

For starters, don't do that!
Do not concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Use Parametrized queries instead.

I'm guessing it's the Dispose - so start by removing just that line and see if the problem goes away. If it does, then you need to look at what you are doing in the Dispose method.

JayantaChatterjee 10-May-14 10:39am

Thanks for Remind me about SQL Injection, I will Use Parametrized Query..

After making comments on those lines its work properly, that's why I posted that lines of codes.
In Data_Con class dispose method code is :
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
protected virtual void Dispose(bool disposing)
{
try
{
if (disposing)
{
conn.Close();
conn.Dispose();
cmd.Dispose();
adpt.Dispose();
dataSet.Dispose();
}
}
catch { }
}
Is this wrong ?

OriginalGriff 10-May-14 10:56am

Try the other way around.
Dispose them in the reverse order they were created: so the connection is last to go.
And never use empty, anonymous catch blocks: at the very least use Debug.WriteLine (or Console.WriteLine) to report the Exception with as much detail as you can - or you don't know what went wrong, and you can't tell that it even did! :laugh:

JayantaChatterjee 10-May-14 11:18am

Sir I crossed checked but there is no error in catch block(which is in Dispose method), and change the formation of the object disposing in that method as you say connection object dispose goes last ..
but its still gives same error.... :-(
Is there any other way to do this(I mean Disposing or memory management) to remove this error??

OriginalGriff 10-May-14 11:28am

No...try taking out all but one Dispose call, and slowly return them until the problem comes back?

JayantaChatterjee 10-May-14 11:44am

Now I think I got the Error root.
If I dispose or Close the connection object in the Dispose method then it gives that error, if I comment that two lines then its okay..
So My question is if I only send that class(Data_Con) to garbage Collection without dispose or close the connection object , is the connection still open??

OriginalGriff 10-May-14 11:49am

Yes...so have a look and see if the connection is used in any other code.
There must be something that is using that connection - directly or indirectly - and you need to find out what it is.

JayantaChatterjee 10-May-14 12:16pm

I debugging my whole project from beginning, but couldn't find any outside code which used the connection object directly or indirectly.<br>
<br>
Actually I create Data_con class object when it needed and after worked done Dispose the Data_con object with dispose method(Its happened on every block in which the Data_con object created like open and close).<br>
Is there any way to close the connection object??

OriginalGriff 10-May-14 12:20pm

Yeah - you call Close or Dispose...:laugh:

Have you looked with "Find All References"? Because I'm sure your Adapter uses it, your Command uses it, and so forth - so it will be used indirectly wherever you reference those.

JayantaChatterjee 10-May-14 12:29pm

I dispose all the objects one after one and at last the connection object.:-(
When I dispose the Adapter object, is that still uses the connection object reference?
I am using only private object in that class..

Error : Attempted to read or write protected memory in c#

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Error : Attempted to read or write protected memory in c#

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