# why can't unload vtkCommonCore.dll

**URL:** https://discourse.vtk.org/t/why-cant-unload-vtkcommoncore-dll/1200
**Category:** Support
**Tags:** jobs
**Created:** [June 24, 2019, 6:26am UTC](https://discourse.vtk.org/t/why-cant-unload-vtkcommoncore-dll/1200 "2019-06-24T06:26:22Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![pingdan](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/p/22d042/32.png) [@pingdan](https://discourse.vtk.org/u/pingdan)
#### Post date: [June 24, 2019, 6:26am UTC](https://discourse.vtk.org/t/why-cant-unload-vtkcommoncore-dll/1200/1 "2019-06-24T06:26:22Z")

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with vs2013, I use vtk in a mfc dll  
(just add four lines #include \<vtkAutoInit.h\>

```
VTK_MODULE_INIT(vtkRenderingFreeType);
VTK_MODULE_INIT(vtkInteractionStyle);
VTK_MODULE_INIT(vtkRenderingOpenGL2);
VTK_MODULE_INIT(vtkRenderingVolumeOpenGL2);
),but I found after the main program load mfc dll and unload the mfc dll,it will occur a crash.it will go to 
void vtkCommonInformationKeyManager::ClassFinalize()
{
  if(vtkCommonInformationKeyManagerKeys)
  {
    // Delete information keys.
    for(vtkCommonInformationKeyManagerKeysType::iterator i =
          vtkCommonInformationKeyManagerKeys->begin();
        i != vtkCommonInformationKeyManagerKeys->end(); ++i)
    {
      vtkInformationKey* key = *i;
      delete key;
    }

```

and show a error as below:

`0x00007FFC465BC782 (vtkCommonCore-8.1.dll) conflict`  
who can tell my why?

---

<div class="post-metadata">

### Author: ![ben.boeckel](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/b/ea5d25/32.png) [@ben.boeckel](https://discourse.vtk.org/u/ben.boeckel)
#### Post date: [June 25, 2019, 1:28pm UTC](https://discourse.vtk.org/t/why-cant-unload-vtkcommoncore-dll/1200/2 "2019-06-25T13:28:06Z")

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Hmm. My guess is that you’re linking against one VTK build, but at runtime, a different one is being found. However, I suspect that unloading the VTK libraries just isn’t supported in general (it’s not a common use case).