6 thoughts on “How to install Python 3.9.1 on Raspberry Pi”

1. followed this on a fresh install of Raspbain, after trying the other install of 3.9.0 on a different sd card but it is failing for the same reason

   sudo update-alternatives –config python
   update-alternatives: error: no alternatives for python

   no error messages other then this

   Installing collected packages: setuptools, pip
   WARNING: The script easy_install-3.9 is installed in ‘/usr/bin/python3.9.1/bin’ which is not on PATH.
   Consider adding this directory to PATH or, if you prefer to suppress this warning, use –no-warn-script-location.
   WARNING: The script pip3.9 is installed in ‘/usr/bin/python3.9.1/bin’ which is not on PATH.
   Consider adding this directory to PATH or, if you prefer to suppress this warning, use –no-warn-script-location.
   Successfully installed pip-20.2.3 setuptools-49.2.1

   Any advice ? This is in a Pi400 16gb sd and full update / upgrade / dist-upgrade was run first and rebooted.

   Reply ↓

   • sorry forgot to add

     pi@raspberrypi:~ $ python -V
     Python 2.7.16

     Reply ↓

   • have you tried https://stackoverflow.com/questions/3402168/permanently-add-a-directory-to-pythonpath ?

     Reply ↓

     • rebooted and the PATH is back to the default. I changed /etc/.bashrc and local but $PATH is the same
       pi@raspberrypi:~ $ echo $PATH
       /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/games:/usr/games

       No matter what I do the PATH wont update

       pi@raspberrypi:~ $ python -V
       Python 2.7.16
       pi@raspberrypi:~ $ python2 -V
       Python 2.7.16
       pi@raspberrypi:~ $ python3 -V
       Python 3.7.3

       python -c ‘import sys; print(sys.path)’
       [”, ‘/home/pi’, ‘/usr/bin/python3.9.1/bin’, ‘/usr/lib/python2.7’, ‘/usr/lib/python2.7/plat-arm-linux-gnueabihf’, ‘/usr/lib/python2.7/lib-tk’, ‘/usr/lib/python2.7/lib-old’, ‘/usr/lib/python2.7/lib-dynload’, ‘/usr/local/lib/python2.7/dist-packages’, ‘/usr/lib/python2.7/dist-packages’, ‘/usr/lib/python2.7/dist-packages/gtk-2.0’]

       pi@raspberrypi:~ $ echo $PATH
       /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/games:/usr/games

       both /etc.bashrc and ~/.bashrc have the following as the last line
       export PYTHONPATH=”${PYTHONPATH}:/usr/bin/python3.9.1/bin”

       but when I reboot and type echo $PATH I get
       pi@raspberrypi:~ $ echo $PATH
       /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/games:/usr/games

       pi@raspberrypi:~ $ . ~/.bashrc
       pi@raspberrypi:~ $ sudo update-alternatives –config python
       update-alternatives: error: no alternatives for python

       Im guessing because the /python3.9.1/bin is not in the path ?

       but I cant get it to add to the path.

       Any idea why ?

       Sorry to keep bugging you with these but I ahve learnt a lot in just looking into the errors

2. ok sorted it by following another install, which is similar to yours.

   sudo apt update
   sudo apt upgrade
   sudo apt-get install -y build-essential tk-dev libncurses5-dev libncursesw5-dev libreadline6-dev libdb5.3-dev libgdbm-dev libsqlite3-dev libssl-dev libbz2-dev libexpat1-dev liblzma-dev zlib1g-dev libffi-dev tar wget vim

   wget https://www.python.org/ftp/python/3.9.1/Python-3.9.1.tar.xz
   tar xf Python-3.9.1.tar.xz
   cd Python-3.9.1
   ./configure –enable-optimizations
   sudo make -j 4
   sudo make altinstall

   adding the alias to file .bash_aliases in your home directory
   alias python=’/usr/local/bin/python3.9′

   pi@raspberrypi:~ $ python -V
   Python 3.9.1
   pi@raspberrypi:~ $ python2 -V
   Python 2.7.16
   pi@raspberrypi:~ $ python3 -V
   Python 3.7.3
   pi@raspberrypi:~ $ python3.9 -V
   Python 3.9.1

   Thanks for your posting it was helpful

   Reply ↓

   • Hi Aaron This was really helpful. thanks for that. I managed to get it working with your instructions.

     Reply ↓