# Undefined symbol when run my CLI modules extensions

**URL:** <https://discourse.slicer.org/t/undefined-symbol-when-run-my-cli-modules-extensions/2393>\
**Category:** Development\
**Created:** [March 21, 2018, 9:06pm UTC](https://discourse.slicer.org/t/undefined-symbol-when-run-my-cli-modules-extensions/2393 "2018-03-21T21:06:46Z")\
**Posts on this page:** 1\
**Showing post:** 5

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**Author:** ![brhoom](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/brhoom/32/1228_2.png) [@brhoom](https://discourse.slicer.org/u/brhoom)\
**Post date:** [March 22, 2018, 8:47am UTC](https://discourse.slicer.org/t/undefined-symbol-when-run-my-cli-modules-extensions/2393/5 "2018-03-22T08:47:52Z")

</div>

I don’t understand, what changed? the extension works before, why I have this incompatibility now with the new [build](https://discourse.slicer.org/t/slicer-r26813-produces-4-9-lib/2379/4) that supposed to be the same as the binary 4.8.1? I thought Cmake take care of these things. I also tested with skipping [RPATH](https://cmake.org/Wiki/CMake_RPATH_handling) but I get the same error.

Thank Jean for the info.

I modify SuperBuild/External\_ITKv4.cmake to enable make ITKV3\_Compatibility. I also enabled the related module in ITKv4-build then rebuilt Slicer. After that, I rebuilt the extension but I got this error

```
undefined symbol: _ZN6vtksys11SystemTools24GetFilenameLastExtensionERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE   

```

I checked it using:  
echo “\_ZN6vtksys11SystemTools24GetFilenameLastExtensionERKNSt7\_\_cxx1112basic\_stringIcSt11char\_traitsIcESaIcEEE” | c++filt  
vtksys::SystemTools::GetFilenameLastExtension(std::\_\_cxx11::basic\_string\<char, std::char\_traits, std::allocator \> const&)

It looks there are some option I need to change in VTK?

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