Python install error "A newer version of the Python launcher is already installed"

Question

I am trying to reinstall Python, so I go control panel > uninstall > Python 3.6.2. It succeeds, but when I try to download 3.6.*, it says that I can't download because there is already a version of Python3 installed.

I tried to clean the registry, deleted all files named "Python", but still see the error. I even deleted the path Python in PATH.

Answer 1

This may be a silly solution, but for me the issue was the Python Launcher still listed in the apps list after the uninstall. Uninstalled it separately, afterwards reinstalled Python without the error.

Answer 2

The installer/uninstaller does not do a good job of cleaning up after itself (and that's being generous). What worked for me:

1. Remove all python binary folders from Program Files and Users\<username>\AppData
2. Clean the PATH of any and all mentions of python
3. Search the registry in Computer\HKEY_CLASSES_ROOT\Installer\Features for any values with python, then delete the containing key. The key names are things like "03CEBFB8CC334B3148F9B330F67264A6" (that's an example, not an actual one, since the actuals I deleted)

#3 is the one that actually got it past the hurdle, but #1 and #2 should be done anyway.