# Run-time error when I run openmc

**URL:** <https://openmc.discourse.group/t/run-time-error-when-i-run-openmc/2425>\
**Category:** User Support\
**Created:** [November 3, 2022, 8:39am UTC](https://openmc.discourse.group/t/run-time-error-when-i-run-openmc/2425 "2022-11-03T08:39:26Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![wangkailong](https://avatars.discourse-cdn.com/v4/letter/w/cab0a1/32.png) [@wangkailong](https://openmc.discourse.group/u/wangkailong)\
**Post date:** [November 3, 2022, 8:39am UTC](https://openmc.discourse.group/t/run-time-error-when-i-run-openmc/2425/1 "2022-11-03T08:39:26Z")

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Dear getlemen and women:  
When I use openmc to use a example ,I meet a RuntimeError. See the picture below for details. Thank you for helping me.

 ![1667464695684](https://global.discourse-cdn.com/free1/uploads/openmc/original/2X/e/ef949c7ba5315418e093fa267a5d8d017c1bfafa.png)

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**Author:** ![paulromano](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/paulromano/32/486_2.png) [@paulromano](https://openmc.discourse.group/u/paulromano)\
**Post date:** [November 3, 2022, 9:32pm UTC](https://openmc.discourse.group/t/run-time-error-when-i-run-openmc/2425/2 "2022-11-03T21:32:20Z")

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@wangkailong This error may occur if the file doesn’t exist or if it has already been opened by another application. Can you confirm that the file `/home/wangkailong/openmc/datalib/endfb80_hdf5/H1.h5` does indeed exist on your system?

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**Author:** ![wangkailong](https://avatars.discourse-cdn.com/v4/letter/w/cab0a1/32.png) [@wangkailong](https://openmc.discourse.group/u/wangkailong)\
**Post date:** [November 4, 2022, 2:34am UTC](https://openmc.discourse.group/t/run-time-error-when-i-run-openmc/2425/3 "2022-11-04T02:34:48Z")

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I’m sure the H1.H5 file is in my system.And it keep in /home/wangkailong/openmc/datalib/endfb80\_hdf5/H1.h5 ,then I also have downloaded HDF5 and HDFView.But this “ERROR: Failed to open HDF5 file with mode ‘r’:  
/home/wangkailong/openmc/datalib/endfb80\_hdf5/H1.h5” appear again.I’m confused and don’t know what to do.Thank you for your reply.  
wangkailong

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**Author:** ![paulromano](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/paulromano/32/486_2.png) [@paulromano](https://openmc.discourse.group/u/paulromano)\
**Post date:** [November 5, 2022, 12:35am UTC](https://openmc.discourse.group/t/run-time-error-when-i-run-openmc/2425/4 "2022-11-05T00:35:49Z")

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@wangkailong I would recommend re-downloading the ENDF/B-VIII.0 library from [here](https://openmc.org/official-data-libraries/) and see if that helps.