BleepingComputer.com: Memory reference error in Vb.exe

Hi,

I am getting the error "The instuction at "0x7c910a19" refrenced memory at "0xffffffff". The memory could not be read" when I exit from the application EXE which is built in VB6.0. I do not get this error when I run the program through Vb environment. Only getting error when I make EXE and run it.

Can somebody help me please with the solution?

Thanks,
Ana

Any number of things might cause that. Can you post the relevant section of code where the crash occurs?

Billy3

Hi Billy,

I am getting error when i run EX and exit from it. I have placed debugger on terminate and unload of main form. But not able to catch the error. I am not getting error when I run program through VB environment. So not able to catch the exact line of code.

Thanks,
Ana

Maybe not the exact line, but we're not going to be able to diagnose a but with just the crashing error message. I suspect being VB6 that you guys losded some kind of COM component and didn't unload it correctly, but I'm not sure.

There are a couple of people here who do (unfortunately) still use VB6; perhaps they'll be able to help with the debugger to run down the problem. (But I can't do that)

Billy3

ana13 we can't really do much with out viewing your code. I also have the same opinion as billy when it comes to vb6. Why are you still using it? Yes this is an argument that has been discussed god knows how many times on the net. But point still stands. Why?

Hi

Keep in mind that 0xffffffff is not a real memory address since
0xffffffff = -1 (using two's complement)

The last time I saw this with VB6 was quite some time ago but if I remember correctly it had to do with a Windows Media Player control or component in the program. Does your program have anything using WMP in it? If so, you should double check that part of the code.

James

James, I don't follow. Memory addresses do not use two's complement.

Billy3

Right, the error is saying that it referenced an invalid memory address. Not that it literally addressed the memory address at location 0xffffffff .

I have encountered people trying to troubleshoot the problem by searching for what was trying to access memory location 0xffffffff and that does not work

James

James, trying to access the literal memory location 0xFFFFFFFF would cause an error message like this. I don't see what about looking for the portion of code causing such things would be wrong. Typically such an access might be caused by dereferencing a uninitialized pointer, though I'm not sure how such would happen in VB.

Billy3

Right again
It doesn't happen in VB, but it is probably what you suggested before...

Quote

and the COM component was probably not written in VB.

A lot of VB6 devs don't go that deep though and look for the error in VB. I guess that was the convoluted point I was trying to make and failed miserably. I apologize for the confusion.

James

I remember seeing this error in a VB6 exe file long ago. I had a little time to dig into my old emails and I think this is what we had come up with (in 2001) but I can't find any documentation supporting it.

What happens is a something (probably a COM object or part of one) gets cleaned up twice on exit and the second time it throws an INVALID_HANDLE_VALUE error. The value of INVALID_HANDLE_VALUE is 0xFFFFFFFF and something in VB6 mistakenly tries to access that INVALID_HANDLE_VALUE value.

Billy is correct that it is possible (if not probable) that it is trying to access 0xFFFFFFFF.

So if that is the case, the program is trying to close and clean up something twice in the regular runtime environment that it is only doing once in the developer environment.

I could be wrong though as I could not find anything online about this in a quick search.

My mistake comes from interpreting 0xFFFFFFFF as -1 in other programming languages

James