Installing SetupTools on 64-bit Windows

Problem: you have 64-bit Python, and a 32-bit installer. This will cause problems for extension modules.

The reasons why the installer doesn't finds Python is the transparent 32-bit emulation from Windows 7. 64-bit and 32-bit programs will write to different parts of the Windows registry.

64-bit: HKLM|HKCU\SOFTWARE\

32-bit: HKLM|HKCU\SOFTWARE\wow6432node\.

This means that the 64-bit Python installer writes to HKLM\SOFTWARE\Python, but the 32-bit setuptools installer looks at HKLM\SOFTWARE\wow6432node\Python (this is handled by windows automatically, programs don't notice). This is expected behavior and not a bug.

Usually, you have these choices:

• the "clean" way: use 32-bit Python if you have to use 32-bit modules or extensions
• the other "clean" way: only use 64-bit installers when using 64-bit Python (see below)
• what the answer above suggests: copy HKLM\SOFTWARE\Python to HKLM\SOFTWARE\wow6432node\Python, but this will cause problems with binary distributions, as 64-bit Python can't load 32-bit compiled modules (do NOT do this!)
• install pure Python modules with setuptools instead of the distutils installer (easy_install or pip)

For setuptools itself, for example, you can't use a 32-bit installer for 64-bit Python as it includes binary files. But there's a 64-bit installer at http://www.lfd.uci.edu/~gohlke/pythonlibs/ (has many installers for other modules too). Nowadays, many packages on PyPi have binary distributions, so you can install them via pip.

Apparently (having faced related 64- and 32-bit issues on OS X) there is a bug in the Windows installer. I stumbled across this workaround, which might help - basically, you create your own registry value HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Python\PythonCore\2.6\InstallPath and copy over the InstallPath value from HKEY_LOCAL_MACHINE\SOFTWARE\Python\PythonCore\2.6\InstallPath. See the answer below for more details.

If you do this, beware that setuptools may only install 32-bit libraries.

NOTE: the responses below offer more detail, so please read them too.

I made a registry (.reg) file that will automatically change the registry for you. It works if it's installed in "C:\Python27":

Download 32-bit version HKEY_LOCAL_MACHINE|HKEY_CURRENT_USER\SOFTWARE\wow6432node\

Download 64-bit version HKEY_LOCAL_MACHINE|HKEY_CURRENT_USER\SOFTWARE\

Yes, you are correct, the issue is with 64-bit Python and 32-bit installer for setuptools.

The best way to get 64-bit setuptools installed on Windows is to download ez_setup.py to C:\Python27\Scripts and run it. It will download appropriate 64-bit .egg file for setuptools and install it for you.

Source: http://pypi.python.org/pypi/setuptools

P.S. I'd recommend against using 3rd party 64-bit .exe setuptools installers or manipulating registry

Create a file named python2.7.reg (registry file) and put this content into it:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Python\PythonCore\2.7]

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Python\PythonCore\2.7\Help]

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Python\PythonCore\2.7\Help\MainPythonDocumentation]
@="C:\\Python27\\Doc\\python26.chm"

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Python\PythonCore\2.7\InstallPath]
@="C:\\Python27\\"

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Python\PythonCore\2.7\InstallPath\InstallGroup]
@="Python 2.7"

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Python\PythonCore\2.7\Modules]

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Python\PythonCore\2.7\PythonPath]
@="C:\\Python27\\Lib;C:\\Python27\\DLLs;C:\\Python27\\Lib\\lib-tk"

And make sure every path is right!

Then run (merge) it and done :)