How do I update Python from 3.4.3 to 3.5? [duplicate]

You can try to use this PPA to replace your current python with 3.5:

https://launchpad.net/~fkrull/+archive/ubuntu/deadsnakes

Usage instructions can be found on the linked webpage.

However, I would recommend installing python 3.5 parallel to 3.4 (under /opt for example).

For that you would need to install from source:

wget https://www.python.org/ftp/python/3.5.1/Python-3.5.1.tar.xz
tar xfvJ Python-3.5.1.tar.xz
cd Python-3.5.1
./configure --prefix=/opt/python3.5
make
# To make idle3.5, you need tk's development to produce tkinter
sudo apt-get install tk8.6-dev
sudo make install

Your python 3.5 interpreter will be located in /opt/python3.5/bin/python3.5. Your Integrated DeveLopment Environment is also found in /opt/python3.5/bin/idle3.5.

To facilitate use you can symlink these files to a location on your $PATH like so:

sudo ln -s /opt/python3.5/bin/python3.5 /usr/local/bin/py3.5
sudo ln -s /opt/python3.5/bin/idle3.5 /usr/local/bin/idle3.5

After this, just typing py3.5 from the command line will use python 3.5, while at the same time, python 3.4 will remain untouched, and will not cause any "breakage" on your system. Also, idle3.5 will bring up the IDLE editor with the python 3.5.1 shell.