[python] How to update Python?

I have version 2.7 installed from early 2012. I can't find any consensus on whether I should completely uninstall and wipe this version before putting on the latest version.

"Soft"-removing old versions? Hard-removing/wiping old versions? Installing over top?

I've seen somewhere a special install/upgrade process using a "segmenting" method of Python installations, keeping different versions separate and apart, but functional. Not sure if this is the standard, de facto way.

I also wonder if Revo gets too overzealous and may cause issues with wiping out still-needed remnants, like environment/PATH variables.

(Win7 x64, 32-bit Python)

This question is related to python python-2.7 installation upgrade windows-7-x64

The answer is


I have always just installed the new version on top and never had any issues. Do make sure that your path is updated to point to the new version though.


  • Official Python .msi installers are designed to replace:

    • any previous micro release (in x.y.z, z is "micro") because they are guaranteed to be backward-compatible and binary-compatible
    • a "snapshot" (built from source) installation with any micro version
  • A snapshot installer is designed to replace any snapshot with a lower micro version.

(See responsible code for 2.x, for 3.x)

Any other versions are not necessarily compatible and are thus installed alongside the existing one. If you wish to uninstall the old version, you'll need to do that manually. And also uninstall any 3rd-party modules you had for it:

  • If you installed any modules from bdist_wininst packages (Windows .exes), uninstall them before uninstalling the version, or the uninstaller might not work correctly if it has custom logic
  • modules installed with setuptools/pip that reside in Lib\site-packages can just be deleted afterwards
  • packages that you installed per-user, if any, reside in %APPDATA%/Python/PythonXY/site-packages and can likewise be deleted

The best solution is to install the different Python versions in multiple paths.

eg. C:\Python27 for 2.7, and C:\Python33 for 3.3.

Read this for more info: How to run multiple Python versions on Windows


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