# Problem installing Python API

**URL:** <https://openmc.discourse.group/t/problem-installing-python-api/5618>\
**Category:** User Support\
**Created:** [June 22, 2025, 6:48am UTC](https://openmc.discourse.group/t/problem-installing-python-api/5618 "2025-06-22T06:48:06Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![valerio69](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/valerio69/32/1192_2.png) [@valerio69](https://openmc.discourse.group/u/valerio69)\
**Post date:** [June 22, 2025, 6:48am UTC](https://openmc.discourse.group/t/problem-installing-python-api/5618/1 "2025-06-22T06:48:06Z")

</div>

I’m experiencing the following issue when attempting to install the Python API for version 0.15.2:

> valerio@XPS13:~/Softwares/openmc-0.15.2/openmc$ python3 -m pip install .  
> Defaulting to user installation because normal site-packages is not writeable  
> Processing /home/valerio/Softwares/openmc-0.15.2/openmc  
> Installing build dependencies … done  
> Getting requirements to build wheel … done  
> Preparing metadata (pyproject.toml) … done  
> Building wheels for collected packages: UNKNOWN  
> Building wheel for UNKNOWN (pyproject.toml) … done  
> Created wheel for UNKNOWN: filename=UNKNOWN-0.15.2-py3-none-any.whl size=1851 sha256=d021163866c248343b7a451cc1d9a3e8acfa70714e70bd5a971409a5c07afa9c  
> Stored in directory: /tmp/pip-ephem-wheel-cache-qpsvobjc/wheels/87/3f/96/909665e98ffdf16b434da829873ddf5298ede3c7823af14b21  
> Successfully built UNKNOWN  
> Installing collected packages: UNKNOWN  
> Successfully installed UNKNOWN-0.15.2

I see that the file pyproject.toml reports:

> description = “OpenMC”  
> dynamic = [“version”]  
> **requires-python = “\>=3.11”**  
> license = {file = “LICENSE”}  
> classifiers = [  
> “Development Status :: 4 - Beta”,  
> “Intended Audience :: Developers”,  
> “Intended Audience :: End Users/Desktop”,  
> “Intended Audience :: Science/Research”,  
> “License :: OSI Approved :: MIT License”,  
> “Natural Language :: English”,  
> “Topic :: Scientific/Engineering”,  
> “Programming Language :: C++”,  
> “Programming Language :: Python :: 3”,  
> “Programming Language :: Python :: 3.11”,  
> “Programming Language :: Python :: 3.12”,  
> “Programming Language :: Python :: 3.13”,  
> ]

However, my Python version is 3.10.12. Is that the problem?

---

<div class="post-metadata">

**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:** [June 23, 2025, 6:39pm UTC](https://openmc.discourse.group/t/problem-installing-python-api/5618/2 "2025-06-23T18:39:28Z")

</div>

Yes, you will need to have Python 3.11+ as required by the pyproject.toml file. OpenMC follows [these guidelines](https://scientific-python.org/specs/spec-0000/) for support of Python versions.

---

<div class="post-metadata">

**Author:** ![valerio69](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/valerio69/32/1192_2.png) [@valerio69](https://openmc.discourse.group/u/valerio69)\
**Post date:** [June 23, 2025, 8:12pm UTC](https://openmc.discourse.group/t/problem-installing-python-api/5618/3 "2025-06-23T20:12:53Z")

</div>

@paulromano, thanks for the information and the link to the guidelines. That’s quite interesting to know.