# SlicerCAT error with hdf5

**URL:** <https://discourse.slicer.org/t/slicercat-error-with-hdf5/23408>\
**Category:** Development\
**Tags:** slicercat\
**Created:** [May 13, 2022, 12:59pm UTC](https://discourse.slicer.org/t/slicercat-error-with-hdf5/23408 "2022-05-13T12:59:20Z")\
**Posts on this page:** 1\
**Showing post:** 15

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**Author:** ![keri](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/keri/32/11618_2.png) [@keri](https://discourse.slicer.org/u/keri)\
**Post date:** [May 16, 2022, 7:40pm UTC](https://discourse.slicer.org/t/slicercat-error-with-hdf5/23408/15 "2022-05-16T19:40:58Z")

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I think the problem is that there are too many HDF5 libs (ITK, VTK, h5py, netCDF4)

In my SlicerCAT I build HDF5 as external project and set it to VTK and ITK. So my system has only one instance of HDF5.  
I just reproduced your “fail” steps on my SlicerCAT on clean Ubuntu 22.04:

```auto
pip_install("h5py")
pip_install("netcdf4")
import h5py
import netCDF4

```

and it didn’t crash:

SlicerCAT is built upon Slicer [564ccb319c099d3772a74aea974d6e29075c7593](https://github.com/Slicer/Slicer/tree/564ccb319c099d3772a74aea974d6e29075c7593) (14 may 2022)

Lately [we had a conversation](https://discourse.slicer.org/t/simpleitk-install-fails-on-windows/23373/8) with @lassoan that it would be good to build HDF5 as an external project.  
It is not a problem but don’t have time for this now.

In the future I will add a PR.

If you can’t wait (one-two months I think) you can take a look how I [configured External\_VTK.cmake and External\_ITK.cmake](https://discourse.slicer.org/t/simpleitk-install-fails-on-windows/23373/9). And there you can find External\_HDF5.cmake but it probably should be modified to allow building against specific HDF5 version (probably you would want h5py to work with the same HDF5 version)

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