Python is an object-oriented, high-level programming language. It is an open source with a large community. Python is used as key languages among the top tech companies like Google. The Python 3.9 stable version has been released with several improvements and security updates. It included multiple new modules, improved existing modules and many other features.
The Debian 9 stretch comes with default Python 2.7 and 3.5. So you can install Python 3.5 directly from the default apt repositories using command
apt install python3 . If you still need to install Python 3.9 on Debian 9, Go ahead with this tutorial.
This tutorial will describe you to how to install Python 3.9 on Debian 9 Stretch Linux system.
Firstly, login to your Debian 9 system with sudo user. After login, update the current packages on your system to update packages.
sudo apt update && sudo apt upgrade
After that, install belwo packages on your system, which is required for the installation of Python 3.9 from source code.
sudo apt install wget build-essential libreadline-gplv2-dev libncursesw5-dev \ libssl-dev libsqlite3-dev tk-dev libgdbm-dev libc6-dev libbz2-dev libffi-dev zlib1g-dev
Installing Python 3.9 on Debian
As you know, the default apt repositories contains Python 3.5 only. So to install latest packages, you need to compile it from source code. Use below steps to install Python 3.9 on Debian Stretch systems.
- Download Python – Download the Python 3.9 source code archive from its official website. alternatively use below wget command to download Python source code.
- Extract Archive – Next, extract the download archive file using the tar command. If required change your directory before extract.
tar xzf Python-3.9.16.tgz
- Compile Python Source – Switch to the extracted directory and configure the source code with enabling optimizations.
- Install Python 3.9 – Finally, run the make command to complete the Python installation. Here
altinstalloption is to install Python separately than default versions.
Wait for the Python installation complete on your system. All done.
Check Python Version
At this step, you have successfully installed Python 3.9 on Debian system. You need to type
python3.9 to use this version. For example, to check the Python version, execute:
python3.9 -VPython 3.9.16
This will also install pip for Python 3.9.
pip3.9 -Vpip 20.2.3 from /usr/local/lib/python3.9/site-packages/pip (python 3.9)
That’s it, You have successfully installed Python 3.9 on Debian 9 (Stretch) Linux system.
This tutorial described you to install Python 3.9 on Debian Linux systems using source code. You can try Python examples via command line.
This doesn’t work.. When I download the python version on my version 3 pi and try to import a package (numpy) I receive this error:
Traceback (most recent call last):
File “/home/pi/.local/lib/python3.9/site-packages/numpy/core/__init__.py”, line 23, in
from . import multiarray
File “/home/pi/.local/lib/python3.9/site-packages/numpy/core/multiarray.py”, line 10, in
from . import overrides
File “/home/pi/.local/lib/python3.9/site-packages/numpy/core/overrides.py”, line 6, in
from numpy.core._multiarray_umath import (
ImportError: libcblas.so.3: cannot open shared object file: No such file or directory
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File “”, line 1, in
File “/home/pi/.local/lib/python3.9/site-packages/numpy/__init__.py”, line 140, in
from . import core
File “/home/pi/.local/lib/python3.9/site-packages/numpy/core/__init__.py”, line 49, in
IMPORTANT: PLEASE READ THIS FOR ADVICE ON HOW TO SOLVE THIS ISSUE!
Importing the numpy C-extensions failed. This error can happen for
many reasons, often due to issues with your setup or how NumPy was
We have compiled some common reasons and troubleshooting tips at:
Please note and check the following:
* The Python version is: Python3.9 from “/usr/local/bin/python3.9”
* The NumPy version is: “1.23.2”
and make sure that they are the versions you expect.
Please carefully study the documentation linked above for further help.
Original error was: libcblas.so.3: cannot open shared object file: No such file or directory
It did work, with “sudo make altinstall”. Where is the executable located? I want to run script, but I don’t know where to point the shebang.
sudo make altinstall
I would also make python3.9 my default python installation, how do i do that?
1. Enter bash shell script
sudo nano ~/.bashrc
2. Enter aliases for python 3.9
3. Save the changes to the script and exit
Ctrl+S followed by Ctrl+X