Solving install issues with Python 3.4 on Windows

Question 1

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:

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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.

Question 2

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

Question 3

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.

Question 4

I had similar issues with Python 3.4x on Windows 8.1. Even after a successful install, the uninstaller would fail in the same way. Ultimately, "Method 1" at the MS forum solved this for me when I ran Microsoft's (Un)installer Fix It.

Question 5

I also had the problem that pip couldn't be installed like @ChrisPosser.

So I deselected pip and the installation went fine. afterwards I restarted the setup, chose "change python" and installed pip. now everything worked like expected.

If you have any problems with windows installers I recommend activating the verbose log like this:

msiexec /i python-2.7.10-1.609.2.msi /lv install-python.log

From the logs I could see that it was the pip install, which was not working.

Question 6

Yes, I faced the same issue, and was working on this for the past one hour. Was trying to uninstall the Python 3.4.1 from the control panel -> uinstall program -> add/remove program, but was facing issues.

This trick worked for me:

Manually deleted the 3.4.1 folder, which was present in my C folders after I installed the 3.4.1

Then I followed these steps:

-> Went to Regedit.exe, checked in both HKEY_CURRENT_USER, HKEY_LOCAL SOFTWARE Folder, and deleted the Python folders there.
-> windows 8 -> Downloads -> 3.4.1 msi setup (Glad I never deleted it)
-> Right clicked on the msi setup and choose the repair option
-> The repair would re install the Python 3.4.1
-> After this, I un-installed the Python 3.4.1
-> Then I deleted the 3.4.1 msi setup.

Rebooted the system, and now, there is no instance of Python 3.4.1 in my system.

Question 7

According to me when environment variables containing name 'Python' are created they somehow becomes related with python. I was unable to open idle (GUI PUTHON) and to uninstall it . Deleting a variable named 'PYTHON PATH' solved my all python related problems.

Question 8

I had 3.7.4 and wanted to move to 2.7.13.
I uninstalled 3.7.4
Tried to install 2.7.13 but got the same error.
There was a 2.7.10 installer(not msi) also present, uninstalling which gave the same error.
So I downloaded 2.7.10 msi, installed it, and then just installed 2.7.13 from the downloaded msi and it worked fine. This overwriting worked because the major version i.e. 2.7 was same for both.

I don't know if this is helpful but after the hours I spent on this, I wanted to write out what worked for me.

Question 9

Yup, I have already installed another version of python. I have uninstalled them using Program features. But still the same issue persisted because of the folder which was present in my C: drive. After deleting them manually, the installation got completed without errors

Question 10

I faced this issue because of 2 conflicting versions of 7zip. Removing them both and installing just one fixed this issue.

Question 11

I had python3.4 installed, then added 3.5, and deleted 3.4. That was a mistake. In trying to get a library to work, I had to go back to 3.4. I uninstalled 3.5, but couldn't uninstall 3.4 (folder deleted).

I ended up searching the registry in rededt32 for "python". There was a Guid folder with a number of entries that had c:\python34 and one more related to the same folder that I deleted. After this, the install worked correctly.

Windows 10.

Question 12

Mine was linked to having installed an older version in the past, only for my own user account. I got around it by telling the installer to install Python for all users.

Question 13

For me none of the suggested fixes worked for me. However checking the option "Install just for me" instead of "Install for all users" (Windows 10) worked for me. So this might be another option to try.