py launcher does not find my Python 2.7

Question

I'm on Windows 7. I have Python 2.7 installed for years. I installed recently Python 3.4. I'm trying to use the new py launcher. When I open the cmd terminal and type py -2, I get this error message: Requested Python version (2) not installed. How can make py aware of my python 2.7 installation?

Note: python 2.7 is installed in a non-standard directory (not in C:\Python27), in case this is the problem.

Answer 1

I found the solution. The registry had wrong entries. As I have a 32 bit version installed I went to HKEY_LOCAL_MACHINE|HKEY_CURRENT_USER\SOFTWARE\wow6432node\Python\PythonCore\2.7\InstallPath and the value was set to C:\Python27 while my installation is in D:\Python27. So I changed all the registry values to match the correct location and it now works fine.

It's been quite a while I installed Python 2.7, but I assume I had Python 2.7 installed first. Then I deleted it and installed pythonxy in this new location. I probably didn't uninstall the previous version correctly.

Answer 2

I had a similar issue with Py Launcher failing to recognize my Python 2.7 install. I found editing the Windows Registry (Windows 10) by adding 2.7 to [HKEY_CURRENT_USER\Software\Python\PythonCore\2.7] solved my problem.

Other Window versions may have the PythonCore key in a different location.

Here is the full export of the tree I added:

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Python\PythonCore\2.7]

[HKEY_CURRENT_USER\Software\Python\PythonCore\2.7\InstallPath]
"ExecutablePath"="C:\\Users\\kcec11\\Python\\Python27\\python.exe"
"WindowedExecutablePath"="C:\\Users\\kcec11\\Python\\Python27\\pythonw.exe"
@="C:\\Users\\kcec11\\Python\\Python27\\"