Exception has been thrown by the target of an invocation.

Question

0.00/5 (No votes)

See more:

Hi,
In my windows application I have overridden one windows application function WndProc. It's to enable Inter-Process-Communication between two exes through windows messages. It's working fine, But, Sometimes, Application crashes at this line base.WndProc(ref m); I dont know what causes the error. Can anybody tell me please. Is there any problem will happen if I remove this line ??
here is the code..

C#

protected override void WndProc(ref Message m)
     {
         switch (m.Msg)
         {
             case Win32.WM_COPYDATA:
                 Win32.CopyDataStruct st = (Win32.CopyDataStruct)Marshal.PtrToStructure(m.LParam, typeof(Win32.CopyDataStruct));
                 string strData = Marshal.PtrToStringUni(st.lpData);

                 if (strData == "msgfromclientexe")
                     timer2.Enabled = true;
                 break;
             default:
                 // let the base class deal with it
                 base.WndProc(ref m);
                 break;
         }
     }

update:

When I dont use base.WndProc(ref m)
MY main function throws an error "Error creating handle"
at this line

App myApp = new App();
myApp.Run(args);

Posted 27-May-14 2:45am

Yesudasan Moses

Updated 27-May-14 3:00am

v2

Add a Solution

Comments

johannesnestler 27-May-14 8:54am

any inner exceptions on your exception?

johannesnestler 27-May-14 8:55am

If you don't handle the message - you want "default handling", so no - you can't just "leave it away" (the base.WndProc call)

Yesudasan Moses 27-May-14 9:00am

When I dont use base.WndProc(ref m)
MY main function throws an error "Error creating handle"
at this line

App myApp = new App();
myApp.Run(args);

Yesudasan Moses 27-May-14 9:09am

this error happens sometimes only,,, but it lets the released application to crash. I will check the inner exception next time and update it.. thanks :)

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Dave Kreskowiak · Answer 1 · 2014-05-27T04:14:00

You don't call that in your default case handler. You call it always, either at the top of your override code or at the bottom, depending on if you want the base default code to handle the message you're overriding or not. But, it either case, the base code must be called to handle all of the messages you're not handling.

THe code below will allow the base code to handle the CopyData message as well as letting your code handle it, adding to the functionality provided by the base code.

C#

protected override void WndProc(ref Message m)
    {
        base.WndProc(ref m);

        switch (m.Msg)
        {
            case Win32.WM_COPYDATA:
                Win32.CopyDataStruct st = (Win32.CopyDataStruct)Marshal.PtrToStructure(m.LParam, typeof(Win32.CopyDataStruct));
                string strData = Marshal.PtrToStringUni(st.lpData);

                if (strData == "msgfromclientexe")
                    timer2.Enabled = true;
                break;
        }
    }

This makes sure that the base code gets a crack at the message before you try to do anything with it.