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“A first chance exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll COM" problem en my COM event in c#

Posted on 2006-06-02
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Last Modified: 2008-01-09
Hi there,

can anyone help? problem doesn't exist in vs2003 only in vs2005 BUT i have half fixed it....



Basically an event arrives in c# from my COM activeX ... when it arrives it appears to be in a different thread... well i think that is what the error msg means.... Hence i wrote a delegate and a method to do the writing for me.

If i put a breakpoint on the Eventhandler before the { , and when it enters ... continue and take off break point it appears not to be in a different thread

If i don't put a breakpoint the good news is i got it working ... it prints the data to the textbox BUT errror msg is still displayed in the output window..

Am i a missing something??

Thanks in advance

Ian

public delegate void WriteToLogCallback(string text);  //this is a delegate to do the job


private void myConnection_Data(int hotlink) // is an event that arrives from my COM dll
        {
            Data myData = (Data)myChannel[0].getData();


            txtNum.Invoke(new WriteToLogCallback(this.WriteToLog), new object[]{myData.num});

//txtNum.Text = myData.num;  // This line used to give errro message and not event write to the text box!!

Etc
.
.



        private void WriteToLog(string text)
        {
            // Set the textbox text.
            txtNum.Text = text; /// Ok it now prints the details to the screen in txtbox but the error msg is still displayed
//A first chance exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll COM


        }
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Question by:ianinspain
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7 Comments
 
LVL 48

Expert Comment

by:AlexFM
ID: 16818928
I think you need to apply Invoke to form and not to control. If num is not string, convert it to string:

this->Invoke(new WriteToLogCallback(this.WriteToLog), new object[]{myData.num.ToString()});

Where does "first chance exception" message appear? In Output window or you have exception dialog?
0
 

Author Comment

by:ianinspain
ID: 16830808
only the output window

0
 

Author Comment

by:ianinspain
ID: 16830813
it appears as soon as i attempt to write anything to the screen ... in the case before i used the delegate ... it was in the event... but it wouldn't write anything to the screen.... now i use a delegate.. the msg occurs also in the delegate method as soon as i attempt to write to the screen .... but at least this time it actually writes something..

Ian
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Author Comment

by:ianinspain
ID: 16830826
heres the actually msg straight from the output window.... it doesn't give me a exception dialog though..

A first chance exception of type 'System.AccessViolationException' occurred in GetRealTime.exe

and now i am doing

this.Invoke............

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LVL 48

Expert Comment

by:AlexFM
ID: 16830926
"First chance exception" message means: exception was thrown somewhere, but was catched and successfully handled. If this doesn't happen in your code, this can be in some .NET libraries. You can ignore this message.
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Author Comment

by:ianinspain
ID: 16841249
hi thanks.. are you saying it isn't important then?

thanks

ian
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LVL 48

Accepted Solution

by:
AlexFM earned 2000 total points
ID: 16841300
First chance exception messages in Output window can be ignored.
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