# Why I am getting below error while Simple-ITK Build using SuperBuild?
**URL:** https://discourse.itk.org/t/why-i-am-getting-below-error-while-simple-itk-build-using-superbuild/7661
**Category:** Uncategorized
**Created:** [November 10, 2025, 6:09am UTC](https://discourse.itk.org/t/why-i-am-getting-below-error-while-simple-itk-build-using-superbuild/7661 "2025-11-10T06:09:26Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Shabina](https://discourse.itk.org/u/Shabina)
#### Post date: [November 10, 2025, 6:09am UTC](https://discourse.itk.org/t/why-i-am-getting-below-error-while-simple-itk-build-using-superbuild/7661/1 "2025-11-10T06:09:26Z")
[6%] Built target SuperBuildSimpleITKSourceReal
[8%] Generating uv/bin/uv
[26%] Built target ITK
[26%] Built target SuperBuildSimpleITKSource
[43%] Built target PCRE2
[60%] Built target Swig
[63%] Creating python virtual environment…
× Failed to download
│ [https://github.com/astral-sh/python-build-standalone/releases/download/20250604/cpython-3.12.11%2B20250604-x86\_64-unknown-linux-gnu-install\_only\_stripped.tar.gz](https://github.com/astral-sh/python-build-standalone/releases/download/20250604/cpython-3.12.11%2B20250604-x86_64-unknown-linux-gnu-install_only_stripped.tar.gz)
├─▶ Request failed after 3 retries
├─▶ error sending request for url
│ ([https://github.com/astral-sh/python-build-standalone/releases/download/20250604/cpython-3.12.11%2B20250604-x86\_64-unknown-linux-gnu-install\_only\_stripped.tar.gz](https://github.com/astral-sh/python-build-standalone/releases/download/20250604/cpython-3.12.11%2B20250604-x86_64-unknown-linux-gnu-install_only_stripped.tar.gz))
├─▶ client error (Connect)
╰─▶ invalid peer certificate: UnknownIssuer
make[2]: \*\*\* [CMakeFiles/SimpleITK\_VENV.dir/build.make:73: venv/bin/python] Error 1
make[1]: \*\*\* [CMakeFiles/Makefile2:203: CMakeFiles/SimpleITK\_VENV.dir/all] Error 2
make: \*\*\* [Makefile:91: all] Error 2
Independently i tried to access the link using wget. I am able to access. Few details on my system.
Ubuntu 22.04
cmake 3.28.1
python 3.14
swig 4.3.1
---
### Author:  [@blowekamp](https://discourse.itk.org/u/blowekamp)
#### Post date: [November 10, 2025, 2:49pm UTC](https://discourse.itk.org/t/why-i-am-getting-below-error-while-simple-itk-build-using-superbuild/7661/2 "2025-11-10T14:49:33Z")
> [@Shabina](#):
>
> w details on my system.
Hello,
Thank you for using and testing the current SimpleITK main or the v3.0.0a1 release.
SimpleITK 3.0 is now using Python to perform the code generation. It is using [uv](https://docs.astral.sh/uv/) to download python and create a virtual environment. It looks like during this step there is a SSL certificate errors.
Is your computer behind a proxy firewall, that may be inspecting/intercepting SSL certificates? Or perhaps there is there is something old with the version of uv, or other software SimpleITK is trying to use.
The code for this step is here:
>
The usage of “uv” and the creation of the virtual environment can be bypassed if the CMake variable “SimpleITK\_Python\_EXECUTABLE” is set.
Please create a virtual environment with python 3.10+ along with installing the following packages:
```auto
jinja2~=3.1
jsonschema~=4.24
pyyaml~=6.0
```
Then set SimpleITK\_Python\_EXECUTABLE to the path of the new python executable in the environment with the required packages. Please let us know if this works for you or if you need further instructions.
---
### Author:  [@Shabina](https://discourse.itk.org/u/Shabina)
#### Post date: [November 13, 2025, 7:42am UTC](https://discourse.itk.org/t/why-i-am-getting-below-error-while-simple-itk-build-using-superbuild/7661/3 "2025-11-13T07:42:25Z")
Thank you so much! it worked. Successfully build and Install Simple-ITK. Thank you