Solving install issues with Python 3.4 on Windows

My issue was that I had a PYTHON_HOME or PYTHON_SOMETHING environment variable set. After removing the environment variable, the installation worked perfectly.

What worked for me, strangely enough, was the "Microsoft Program Install and Uninstall troubleshooter"

The "deselect pip" solution did not work for me.

My Python 3.4.1 install was failing with the same "A program run as part of the setup did not finish as expected" error. I tried both installing it on top of Python 3.4.0 and installing it in a new folder, but got the same error. I tried uninstalling Python 3.4.0 first, but got the error during the uninstall, as well.

I ran that Microsoft utility, which helped me uninstall 3.4.0, and was then able to install 3.4.1 cleanly. The utility has options for both problematic installs and uninstalls, so it may help even if you're doing a new install, not an upgrade.

I'm running 64-bit Windows 7, but was working with 32-bit Python versions.

After some looking online I found (here) that the issue was related to conflicting pip installs (I have a version already installed for Python 2.7 and apparently this is not compatible with the version that ships with Python 3.4.

To get around this issue I simply de-selected pip from the install options shown below and the install went ahead smoothly:

Run installer again and select PIP installation.

If the PIP fails to install with the same error, you may want to check environmental variables using a tool like http://eveditor.com/ which enables to check whether they are valid. If you had another version installed before, you most likely have wrong PYTHONHOME and PYTHONPATH variables. Fix them by setting them to relevant paths. e.g. PYTHONHOME=C:\python27 and PYTHONPATH=c:\python27\Lib

You will then be able to run and install PIP.