Value error trying to install Python for Windows e

Question

I have Microsoft Visual Studio 2008 installed already. I downloaded the zip file Python for Windows extensions and extracted the contents into my Python27 folder. There's now a subfolder called pywin32-214. (Is the 32 part a problem? I'm on a 64-bit system.) Here's a transcript from the command line:

C:\Python27\pywin32-214>setup.py -q install
Building pywin32 2.7.214.0
Traceback (most recent call last):
  File "C:\Python27\pywin32-214\setup.py", line 2152, in <module>
    ('', ('pywin32.pth',)),
  File "C:\Python27\lib\distutils\core.py", line 152, in setup
    dist.run_commands()
  File "C:\Python27\lib\distutils\dist.py", line 953, in run_commands
    self.run_command(cmd)
  File "C:\Python27\lib\distutils\dist.py", line 972, in run_command
    cmd_obj.run()
  File "C:\Python27\pywin32-214\setup.py", line 1251, in run
    install.run(self)
  File "C:\Python27\lib\distutils\command\install.py", line 563, in run
    self.run_command('build')
  File "C:\Python27\lib\distutils\cmd.py", line 326, in run_command
    self.distribution.run_command(command)
  File "C:\Python27\lib\distutils\dist.py", line 972, in run_command
    cmd_obj.run()
  File "C:\Python27\pywin32-214\setup.py", line 596, in run
    build.run(self)
  File "C:\Python27\lib\distutils\command\build.py", line 127, in run
    self.run_command(cmd_name)
  File "C:\Python27\lib\distutils\cmd.py", line 326, in run_command
    self.distribution.run_command(command)
  File "C:\Python27\lib\distutils\dist.py", line 972, in run_command
    cmd_obj.run()
  File "C:\Python27\lib\distutils\command\build_ext.py", line 340, in run
    self.build_extensions()
  File "C:\Python27\pywin32-214\setup.py", line 858, in build_extensions
    self.compiler.initialize()
  File "C:\Python27\lib\distutils\msvc9compiler.py", line 383, in initialize
    vc_env = query_vcvarsall(VERSION, plat_spec)
  File "C:\Python27\lib\distutils\msvc9compiler.py", line 299, in query_vcvarsal
l
    raise ValueError(str(list(result.keys())))
ValueError: [u'path']

I don't know what to make of this. Help?

Answer 1

Another possible reason for this problem to appear is that you have just installed Visual Studio and the command prompt you're using had been hanging around from the time before the installation.

This is because MSVC installer sets few environment variables and one of these variables ( VS90COMNTOOLS )has to be set for vcvarsall.bat to execute correctly. But each running program in Windows holds its own local copy of environment variables that gets inherited (copied) from parent process upon child start-up. Thus, after child has started, it does not receive alterations performed on the system-level envvars. And the only way of getting updated environment variables is trough spawning a new instance of a child process with parent that has updated version of envvars.