# No cross\_sections.xml file was specified in materials.xml or in the OPENMC\_CROSS\_SECTIONS

**URL:** https://openmc.discourse.group/t/no-cross-sections-xml-file-was-specified-in-materials-xml-or-in-the-openmc-cross-sections/3306
**Category:** User Support
**Created:** [August 11, 2023, 12:40pm UTC](https://openmc.discourse.group/t/no-cross-sections-xml-file-was-specified-in-materials-xml-or-in-the-openmc-cross-sections/3306 "2023-08-11T12:40:26Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![umarov](https://avatars.discourse-cdn.com/v4/letter/u/ecd19e/32.png) [@umarov](https://openmc.discourse.group/u/umarov)
#### Post date: [August 11, 2023, 12:40pm UTC](https://openmc.discourse.group/t/no-cross-sections-xml-file-was-specified-in-materials-xml-or-in-the-openmc-cross-sections/3306/1 "2023-08-11T12:40:26Z")

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[aaa.ipynb](https://openmc.discourse.group/uploads/short-url/fh0ZBirLd82RkQ782bndaaO6oGl.ipynb) (11.7 KB)  
Hello, i am receiving this error even i have a cross section file. Can not find what is the problem. help me please to find an error.

 ![image](https://global.discourse-cdn.com/free1/uploads/openmc/original/2X/a/a96795d26cfee63913a4e96f9e7dd3a5cfd76970.png)

 ![image](https://global.discourse-cdn.com/free1/uploads/openmc/original/2X/4/419f732820ed9d414ebcf1d660eb1bafb535e7b8.png)

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### Author: ![jimmyvdw](https://avatars.discourse-cdn.com/v4/letter/j/ce73a5/32.png) [@jimmyvdw](https://openmc.discourse.group/u/jimmyvdw)
#### Post date: [August 11, 2023, 12:54pm UTC](https://openmc.discourse.group/t/no-cross-sections-xml-file-was-specified-in-materials-xml-or-in-the-openmc-cross-sections/3306/2 "2023-08-11T12:54:39Z")

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Hello @umarov, your syntax for defining the cross\_sections.xml file is incorrect. cross\_sections needs to be defined in the following way:

```auto
openmc.Materials.cross_sections = '/mnt/d/openmc/endfb80_hdf5/cross_sections.xml'

```

Having replaced this in your .ipynb script and replacing the path directory with my own, the script ran without error.  
[aaa.ipynb](https://openmc.discourse.group/uploads/short-url/fSUin9j6YcCTdZXOJ9n5JLsODuc.ipynb) (5.2 KB)

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### Author: ![umarov](https://avatars.discourse-cdn.com/v4/letter/u/ecd19e/32.png) [@umarov](https://openmc.discourse.group/u/umarov)
#### Post date: [August 11, 2023, 12:59pm UTC](https://openmc.discourse.group/t/no-cross-sections-xml-file-was-specified-in-materials-xml-or-in-the-openmc-cross-sections/3306/3 "2023-08-11T12:59:36Z")

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oh, its working! Appreciate a lot your help!!!