# AccessViolationException when exit
**URL:** https://discourse.vtk.org/t/accessviolationexception-when-exit/12157
**Category:** Support
**Created:** [August 16, 2023, 6:13am UTC](https://discourse.vtk.org/t/accessviolationexception-when-exit/12157 "2023-08-16T06:13:23Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@liuzhongshu](https://discourse.vtk.org/u/liuzhongshu)
#### Post date: [August 16, 2023, 6:13am UTC](https://discourse.vtk.org/t/accessviolationexception-when-exit/12157/1 "2023-08-16T06:13:24Z")
My .net WPF application use [Activiz.net](http://Activiz.net) 5.8, and sometimes will get an exception on exit.
System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
at Kitware.VTK.vtkObjectBase.vtkObjectBase\_UnRegister\_12(HandleRef pThis, HandleRef o)
at Kitware.VTK.vtkObjectBase.Dispose(Boolean disposing)
at Kitware.VTK.vtkOpenGLRenderer.Dispose(Boolean disposing)
at Kitware.mummy.Runtime.WrappedObject.Finalize()
This exception happens very rarely, usually when it runs for a long time (several hours) and exits.
How to find the cause of this excepton?
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### Author:  [@jaswantp](https://discourse.vtk.org/u/jaswantp)
#### Post date: [August 17, 2023, 2:08pm UTC](https://discourse.vtk.org/t/accessviolationexception-when-exit/12157/2 "2023-08-17T14:08:04Z")
@mwestphal
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### Author:  [@mwestphal](https://discourse.vtk.org/u/mwestphal)
#### Post date: [August 17, 2023, 2:21pm UTC](https://discourse.vtk.org/t/accessviolationexception-when-exit/12157/3 "2023-08-17T14:21:50Z")
@LucasGandel @lgivord
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### Author:  [@mwestphal](https://discourse.vtk.org/u/mwestphal)
#### Post date: [August 17, 2023, 2:22pm UTC](https://discourse.vtk.org/t/accessviolationexception-when-exit/12157/4 "2023-08-17T14:22:25Z")
@liuzhongshu Activiz 5.8 is very old, I’m not sure you will find much help with it.
> **[ActiViz - 3D Visualization Library for .Net C# and Unity | Kitware](https://www.kitware.eu/activiz/)**
>
> Unleash the power of the Visualization Toolkit for your 3D content in C#, .Net and Unity Software. Integrate 3D visualization in your application easily.
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### Author:  [@lgivord](https://discourse.vtk.org/u/lgivord)
#### Post date: [August 17, 2023, 2:26pm UTC](https://discourse.vtk.org/t/accessviolationexception-when-exit/12157/5 "2023-08-17T14:26:19Z")
maybe @alexy.pellegrini may have an idea 🤔
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### Author:  [@LucasGandel](https://discourse.vtk.org/u/LucasGandel)
#### Post date: [August 22, 2023, 11:07am UTC](https://discourse.vtk.org/t/accessviolationexception-when-exit/12157/6 "2023-08-22T11:07:18Z")
You might want to check if this still happens with the latest version by requesting a trial version on the Activiz website.
Disposing the renderer and other VTK objects on the WindowsFormHost “closing” event (or any other event triggered before the exception) might also help.
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### Author:  [@liuzhongshu](https://discourse.vtk.org/u/liuzhongshu)
#### Post date: [August 24, 2023, 1:52am UTC](https://discourse.vtk.org/t/accessviolationexception-when-exit/12157/7 "2023-08-24T01:52:43Z")
@LucasGandel Thanks, I tried Dispose, but the problem still exists.
I will try using a new trial version to compare, but my code is old, I need to modify the code first to be compatible with the new version.