Compiling new Pythons on old Windows compilers

Michael Torrie torriem at
Sun Mar 12 23:26:31 EDT 2017

On 03/12/2017 02:45 PM, eryk sun wrote:
> On Sun, Mar 12, 2017 at 5:02 PM, Eric Frederich
> <eric.frederich at> wrote:
>> Any idea why compatibility was dropped recently?  There used to be a PC
>> directory with different VS directories in the source tree, now it isn't
>> there any more.
> CPython 3.5+ uses the Universal CRT on Windows, which is a system
> component in Vista and later (a recommended update for Windows
> versions prior to 10). See this blog post:

Hmm, this is going to be a huge problem for Python users that work with
proprietary software that is fixed to specific versions of MSCVRT.  The
idea that everyone should just update their builds to the latest
universal runtime is a good one, but it's just not going to happen
across the entire software industry anytime soon.  Especially for
existing releases.  Looks like Python 3 is a no go for Eric.

The runtime mixing issue has always been a problem for Windows
developers.  Not sure the universal runtime really solves it!

More information about the Python-list mailing list