Advertisement
Advertisement


error: Unable to find vcvarsall.bat


Question

I tried to install the Python package dulwich:

pip install dulwich

But I get a cryptic error message:

error: Unable to find vcvarsall.bat

The same happens if I try installing the package manually:

> python setup.py install
running build_ext
building 'dulwich._objects' extension
error: Unable to find vcvarsall.bat
2017/10/23
1
856
10/23/2017 4:32:01 PM


I found the solution. I had the exact same problem, and error, installing 'amara'. I had mingw32 installed, but distutils needed to be configured.

  1. I have Python 2.6 that was already installed.
  2. I installed mingw32 to C:\programs\mingw\
  3. Add mingw32's bin directory to your environment variable: append c:\programs\MinGW\bin; to the PATH
  4. Edit (create if not existing) distutils.cfg file located at C:\Python26\Lib\distutils\distutils.cfg to be:

    [build]
    compiler=mingw32
    
  5. Now run easy_install.exe amara.

Make sure environment is set by opening a new cmd.exe.

2013/11/15

You can install compiled version from http://www.lfd.uci.edu/~gohlke/pythonlibs/

2011/05/12

If you want to compile with Visual Studio C++ instead of mingw...

  1. Run python.exe to display which version of VC++ it was compiled with (example shown below).

    It is important to use the corresponding version of the Visual C++ compiler that Python was compiled with since distilutils's get_build_version prevents mixing versions (per Piotr's warning).

    • Yellow (top) is Python 2.7, compiled with MSC v.1500 (Visual Studio C++ 2008)
    • Red (bottom) is Python 3.4.1, compiled with MSC v.1600 (Visual Studio C++ 2010)

    Example from the command line showing Python 2.7 compiled with MSC v.1500 and Python 3.4.1 compiled with MSC v.1600

  2. Use the table below[1] to match the internal VC++ version with the corresponding Visual Studio release:

    MSC v.1000 -> Visual C++ 4.x        
    MSC v.1100 -> Visual C++ 5          
    MSC v.1200 -> Visual C++ 6          
    MSC v.1300 -> Visual C++ .NET       
    MSC v.1310 -> Visual C++ .NET 2003  
    MSC v.1400 -> Visual C++ 2005  (8.0)
    MSC v.1500 -> Visual C++ 2008  (9.0)
    MSC v.1600 -> Visual C++ 2010 (10.0)
    MSC v.1700 -> Visual C++ 2012 (11.0)
    MSC v.1800 -> Visual C++ 2013 (12.0)
    MSC v.1900 -> Visual C++ 2015 (14.0)
    MSC v.1910 -> Visual C++ 2017 (15.0)
    MSC v.1911 -> Visual C++ 2017 (15.3)
    MSC v.1912 -> Visual C++ 2017 (15.5)
    MSC v.1913 -> Visual C++ 2017 (15.6)
    MSC v.1914 -> Visual C++ 2017 (15.7)
    MSC v.1915 -> Visual C++ 2017 (15.8)
    MSC v.1916 -> Visual C++ 2017 (15.9)   
    
  3. Download and install the corresponding version of Visual Studio C++ from the previous step.
    Additional notes for specific versions of VC++ are listed below.

    Notes for Visual Studio C++ 2008

    For only the 32-bit compilers, download Visual Studio C++ 2008 Express Edition.

    For the 64-bit compilers[2][3], download Windows SDK for Windows 7 and .NET Framework 3.5 SP1.

    • Uncheck everything except Developer Tools >> Visual C++ Compilers to save time and disk space from installing SDK tools you otherwise don't need.

    Notes for Visual Studio C++ 2010

    According to Microsoft, if you installed Visual Studio 2010 SP1, it may have removed the compilers and libraries for VC++.
    If that is the case, download Visual C++ 2010 SP1 Compiler Update.

    Notes for Visual Studio C++ 2015

    If you don't need the Visual Studio IDE, download Visual Studio C++ 2015 Build Tools.

    Notes for Visual Studio C++ 2017

    If you don't need the Visual Studio IDE, download Build Tools for Visual Studio 2017.

    Suggestion: If you have both a 32- and 64-bit Python installation, you may also want to use virtualenv to create separate Python environments so you can use one or the other at a time without messing with your path to choose which Python version to use.

According to @srodriguex, you may be able to skip manually loading the batch file (Steps 4-6) by instead copying a few batch files to where Python is searching by following this answer. If that doesn't work, here are the following steps that originally worked for me.

  1. Open up a cmd.exe

  2. Before you try installing something which requires C extensions, run the following batch file to load the VC++ compiler's environment into the session (i.e. environment variables, the path to the compiler, etc).

    Execute:

    • 32-bit Compilers:

      Note: 32-bit Windows installs will only have C:\Program Files\ as expected

      "C:\Program Files (x86)\Microsoft Visual Studio 9.0\Common7\Tools\vsvars32.bat"

    • 64-bit Compilers:

      "C:\Program Files (x86)\Microsoft Visual Studio 9.0\Common7\Tools\vsvars64.bat"

      Note: Yes, the native 64-bit compilers are in Program Files (x86). Don't ask me why.
      Additionally, if you are wondering what the difference between vcvars64.bat and vcvarsx86_amd64.bat or more importantly the difference between amd64 and x86_amd64, the former are for the native 64-bit compiler tools and the latter are the 64-bit cross compilers that can run on a 32-bit Windows installation.

    Update:
    If for some reason you are getting error: ... was unexpected at this time. where the ... is some series of characters, then you need to check that you path variable does not have any extraneous characters like extra quotations or stray characters. The batch file is not going to be able to update your session path if it can't make sense of it in the first place.

  3. If that went well, you should get one of the following messages depending on which version of VC++ and which command you ran:

    For the 32-bit compiler tools:
    Setting environment for using Microsoft Visual Studio 20xx x86 tools.

    For the 64-bit compiler tools:
    Setting environment for using Microsoft Visual Studio 20xx x64 tools.

  4. Now, run the setup via python setup.py install or pip install pkg-name

  5. Hope and cross your fingers that the planets are aligned correctly for VC++ to cooperate.

2018/12/12

What's going on? Python modules can be part written in C or C++ (typically for speed). If you try to install such a package with Pip (or setup.py), it has to compile that C/C++ from source. Out the box, Pip will brazenly assume you the compiler Microsoft Visual C++ installed. If you don't have it, you'll see this cryptic error message "Error: Unable to find vcvarsall.bat".

The prescribed solution is to install a C/C++ compiler, either Microsoft Visual C++, or MinGW (an open-source project). However, installing and configuring either is prohibitively difficult. (Edit 2014: Microsoft have published a special C++ compiler for Python 2.7)

The easiest solution is to use Christoph Gohlke's Windows installers (.msi) for popular Python packages. He builds installers for Python 2.x and 3.x, 32 bit and 64 bit. You can download them from http://www.lfd.uci.edu/~gohlke/pythonlibs/


If you too think "Error: Unable to find vcvarsall.bat" is a ludicrously cryptic and unhelpful message, then please comment on the bug at http://bugs.python.org/issue2943 to replace it with a more helpful and user-friendly message.

For comparison, Ruby ships with a package manager Gem and offers a quasi-official C/C++ compiler, DevKit. If you try to install a package without it, you see this helpful friendly useful message:

Please update your PATH to include build tools or download the DevKit from http://rubyinstaller.org/downloads and follow the instructions at http://github.com/oneclick/rubyinstaller/wiki/Development-Kit

You can read a longer rant about Python packaging at https://stackoverflow.com/a/13445719/284795

2017/05/23

You'll need to install a Microsoft compiler, compatible with the compiler used to build Python. This means you need Visual C++ 2008 (or newer, with some tweaking).

Microsoft now supplies a bundled compiler and headers just to be able to compile Python extensions, at the memorable URL:

Microsoft Visual C++ Compiler for Python 2.7

http://aka.ms/vcpython27

This is a relatively small package; 85MB to download, installable without admin privileges, no reboot required. The name is a little misleading, the compiler will work for any Python version originally compiled with Visual C++ 2008, not just Python 2.7.

If you start a Python interactive prompt or print sys.version, look for the MSC version string; if it is MSC v.1500 you can use this tool.

From the original announcement to the distutils list:

Microsoft has released a compiler package for Python 2.7 to make it easier for people to build and distribute their C extension modules on Windows. The Microsoft Visual C++ Compiler for Python 2.7 (a.k.a. VC9) is available from: http://aka.ms/vcpython27

This package contains all the tools and headers required to build C extension modules for Python 2.7 32-bit and 64-bit (note that some extension modules require 3rd party dependencies such as OpenSSL or libxml2 that are not included). Other versions of Python built with Visual C++ 2008 are also supported, so "Python 2.7" is just advertising - it'll work fine with 2.6 and 3.2.

Note that you need to have setuptools 6.0 or newer installed (listed in the system requirements on the download page). The project you are installing must use setuptools.setup(), not distutils or the auto-detection won't work.

Microsoft has stated that they want to keep the URL stable, so that automated scripts can reference it easily.

2014/12/15