Compiling a 64 bit Version of PyISAPIe

image Welcome to a veritable novella. I’ll jump straight to the end – there is no happy outcome, as yet, to this post there is a happy outcome! I have compiled a 64 bit PyISAPIe DLL (a program that runs Python at high speed under IIS), and it is up and running on Windows Server 2008 and IIS7. Many thanks to Phillip Stabon, the creator of PyISAPIe, for additional help, and for the latest version of PyISAPIe which makes compilation for different set ups much easier.

Some background information – I’ve not done any C++ for 10 years (and even then my most advanced program was to finish off a code sample on a hotel register for pirates – of the traditional kind). Also I’ve never used Subversion. Hence there are lots of pictures, and every step is detailed. If there’s anything missing let me know.

I’m not sure why I started doing this – the performance of Python using 32-bit version is fine, and since I started working on this Phillip Stabon, has mentioned he will be making a 64 bit DLL himself. However as there are many different versions of Python around, and different GIS tools rely on different versions it seemed a good idea to document how to do this from scratch.

In this example I’m using Visual Studio 2008, and a number of other tools that are detailed as I go along. I’ve also got the 64 bit compilation tools installed. There are a few notes from Phillip on compiling it for Windows 64-bit in the discussion lists (see quoted text underneath the post). Since this post was first published there is a newer discussion in the forums.

Anyway “How to Compile PyISAPIe for a 64-bit Server in 5 Easy Steps!”…

1. Get 64-bit Python

You’ll need a 64 bit version of Python. All my scripts were running and developed using Python 2.5.4 so I wanted to compile PyISAPIe to work with this.

The Python downloads are here. I initially thought that as my server has an Intel processor I should use the version for Win64-Itanium users. However it appears Itanium is only used on some very high spec servers, and I should actually use the python-2.5.4.amd64.msi file. To quote the Python site:

The binaries for AMD64 will also work on processors that implement the Intel 64 architecture (formerly EM64T), i.e. the architecture that Microsoft calls x64, and AMD called x86-64 before calling it AMD64. They will not work on Intel Itanium Processors (formerly IA-64).

If you are using the Itanium Python version on a x64 machine you’ll likely end up with the following error during compilation:

Error    10    fatal error LNK1112: module machine type ‘IA64’ conflicts with target machine type ‘x64’    python25.lib

The Python files are downloaded in a MSI (Microsoft Installer) file, and as I’m developing on a 32-bit laptop (to install on a 64-bit server later) I couldn’t install Python to access the files.


To workaround this I found a useful program called Les MSIérables. This extracts the files contained in an MSI without needing to install anything. I Had to click a few times around the interface before the extract button worked, but then I had a shiny new copy of the 64-bit Python files ready on my machine.


2. Get the PyISAPIe Source

I originally downloaded a zip of the latest PyISAPIe source code. However this is not the way to do things.. The build has an automated step which checks something in Subversion (or SVN – an online source control system), so the source code you compile needs to be a check-out. If you don’t do this you’ll get errors later on such as:

Error 2 fatal error C1083: Cannot open include file: 'Revision.h': No such file or directory

To connect to SubVersion I’d recommend downloading TortoiseSVN (in fact as one of its .exe tools is used in a pre-build step later on – its a requirement). This adds a context menu to Windows Explorer that allows you to connect to SVN and get the latest code. Set up a new folder in Explorer, then right click and select SVN Checkout.image

The URL of the repository for the latest PyISAPIe code is Entering this URL and Clicking OK should start downloading the latest source files via the magic of the Internet.


3. Configure the Visual Studio Project

Once the source code has downloaded you should be able to open up the PyISAPIe.sln file which references the PyISAPIe.vcproj C++ project file. This is set up to compile the 32-bit version by default. You’ll want to change this using Build >> Configuration Manager >> x64. If this is the first time you are compiling a 64-bit DLL you’ll need to create a “New Solution Platform” as shown below:


If you try to compile now you may get the following error:

Error 2 fatal error C1189: #error :  Please define PYI_PY_VERSION at the project level.

We need to tell the compiler the appropriate Python version to use. This can be set by going to Project >> Properties >>  Configuration Properties >> C/C++ >> Preprocessor. If these options seem to be missing then make sure the project itself is selected in the Solution Explorer when clicking on Properties.

I’m using 2.5.4 so I set this value to be PY_25_4 (a list of valid codes can be seen in PyISAPIe.h from line 25 onwards). Also change the WIN32 variable to WIN64.


Another compile, another error (again apparently fatal):

fatal error C1083: Cannot open include file: 'Python25/include/Python.h': No such file or directory

Looking at line 84 in PyISAPIe.h you can see the header file wants to include the Python files:

#include <Python25/include/Python.h>
#include <Python25/include/structmember.h>
#include <Python25/include/frameobject.h>

To allow these files to be correctly referenced I copied the entire Python25 folder (see step 1) into a new Python\x64 folder. The folder structure should now look something like this:


The project is set up to look for the Python files in the Python\x64 folder (for 64 bit release builds) by default. This setting can be seen in the “Additional Include Directories” shown below. The same project can be used with different versions of Python by adding folders such as Python\x64\Python26 and changing the project environment variables.


4. Making the Pre-build Step

In the original project file there is a pre-build step that checks something in SubVersion (its description is “Subversion Revision Scan”). It can be seen at Project >> Properties >> Configuration Properties >> Build Events >> Pre-Build Event:


It runs the following command from the (Windows not Visual Studio) command line:

subwcrev . PyISAPIe\ PyISAPIe\Revision.h

Fortunately the command line tool SubWCRev is downloaded as part of TortoiseSVN. If you don’t have the prebuild step set up correctly then you may receive the following errors:

error PRJ0019: A tool returned an error code from "Subversion Revision Scan" 

The syntax for this command is:

SubWCRev WorkingCopyPath [SrcVersionFile DstVersionFile] [-nmdfe]

Where WorkingCopyPath is the path to the working copy being checked. If you aren’t using a copy of the sourcecode from SVN then you will receive errors such as “SubWCRev : ‘D:\PyISAPie’ is not a working copy.” If you have only just installed TortoiseSVN then make sure you log off or restart Windows so that your environment variables are updated.


The prebuild step should work “out of the box”, however if you still get errors in Visual Studio then running the following commands (pointing to your project folders) from a Windows Shell may provide more useful debugging information.

subwcrev \ Revision.h

All that is actually required by this pre-build step is to generate a Revision.h file of 5 lines..

5. Compile!

Another attempt at compiling and I get:

Error 14 fatal error LNK1104: cannot open file 'python25_d.lib'

From this post I read “python25_d.dll is the debug version. If you want to compile against python25.dll instead, you need to build a Release build of your application, not a Debug build. Or, you can go to and download the debug python25_d.lib and python25_d.dll.”

I changed my build to Release and on the next compile…it worked! And look I have proof..



I then set up the PyISAPIe.DLL on IIS7 (using the same process as I detailed here), but using my newly compiled 64-bit, and using the DefaultAppPool which should run 64 bit applications. I also installed the Python 2.5.4 for 64-bit AMD processors (the same MSI as detailed above).

Unfortunately I currently get HTTP 404.4 errors, with nothing in the logs of use to help diagnose further. I suspect the references to WIN32 may be the issue, but I’ve no idea what to change them to. I’m posting to the PyISAPIe forum with the hope of trying to get this working, and hope that this is not the final revision of this post.

16 views shared on this article. Join in...

  1. Phillip says:

    Hi there,

    While I’ll be posting some details on the PyISAPIe list later regarding changes in the new version to make this process easier, I just thought I’d mention a few things that could help you in the future-

    – PYI_PY_VERSION can be defined in the project settings, under C++/Preprocessor. This is the easiest way to compile for different versions because no source changes are required.

    – You can add additional include and library directories at the project settings level rather than the Visual Studio settings level, which can help in some cases.

    – If SubWCRev wasn’t working from Visual Studio but was from the command line, all I can suggest is to log out and back into your Windows account to be sure that your PATH has been updated everywhere (it works in Windows 7 right after installing TortoiseSVN).

    Thank you for this guide, I’m positive that it will be a great help to those compiling the project themselves.

  2. geographika says:

    Thanks for the tips. I’ve updated the post to include these, and went through the steps with the latest sourcecode.
    I should have realised the PATH had not been updated having wrote about it last week…!
    All is working well, and the new project set up makes it easy to compile for 32 bit or 64 bit, with many different Python versions.

  3. Jonathan Mayer says:

    Fantastic work ( you’re on my favourites list!!)

    You don’t happen to have a copy of the dll do you,

    Cheers Jonathan 😉

  4. geographika says:

    Thanks Jonathan.
    You can get a copy of the 64 bit DLL for Python 2.5 at

  5. chris says:

    Great work and an excellent tutorial!
    I’m struggling, getting mod_python/mod_wsgi to work under Apache 2.2 compiled for 64-bit Windows for a while… After reading this, I definitely will give IIS7+PyISAPIe a try.

  6. This is an awesome article, thank you!!

    I’ve successfully compiled this project to 64bit against Python 2.7. However, when I set up the ISAPI filter in IIS I keep getting a

    The specified module could not be found. (0x8007007e)

    error. As far as I can tell, IIS has full access to that file (I’ve gone as far as giving the Users group and IUSR and Network Service full read/write access). Is there anything else likely to be going on here? Not sure if there might be issues loading the python bindings or something? Any ideas would be much appreciated!

  7. Seth, I’ve followed all those steps as far as I can see (I’m using IIS 7), and the server has been rebooted. Is there any way I can check that the PyISAPIe library works without hooking in IIS? Thanks so much for this :)

  8. geographika says:

    As far as I know there is no wat to check outside of IIS. Does the script produce the “module” error/

    What I have found useful when getting errors is to use Process Monitor to see what DLLs Windows is looking for, and any errors if it can’t find them or if it does not have the correct security settings.

  9. Thanks! Yeah, its the script producing the module error. Will try process monitor and see if that reveals anything.

    BTW, as a sense check, downloaded your x64 bit version and the 2.5.4 amd build you linked – this “works”, although complains about a ctypes module not being present in python. I checked and it seems to be there in 2.7 builds but not the 2.5.4 for some reason?

    have joined the pyisapie email list now so will try and stop bugging you now! :)

  10. Quaspam says:

    Hi thanks for the great article, i have a very stupid question if i may say, i followed about every step you mentioned and i am stuck when the build gets to the linking stage, it gave the following error:
    Error LNK1104: cannot open file ‘python27.lib’
    here is my build command line:

    /OUT:"x64\Release\PyISAPIe.dll" /INCREMENTAL:NO /NOLOGO /LIBPATH:"C:\pyisapie\Python\x64\Python27\libs" /LIBPATH:"C:\pyisapie\Python\x64\Python26\libs" /LIBPATH:"C:\pyisapie\Python\x64\Python25\libs" /DLL "kernel32.lib" "user32.lib" "gdi32.lib" "winspool.lib" "comdlg32.lib" "advapi32.lib" "shell32.lib" "ole32.lib" "oleaut32.lib" "uuid.lib" "odbc32.lib" "odbccp32.lib" /NODEFAULTLIB:"libc libcmt msvcrt" /DEF:"PyISAPIe.def" /MANIFEST /ManifestFile:"x64\Release\PyISAPIe.dll.intermediate.manifest" /ALLOWISOLATION /MANIFESTUAC:"level='asInvoker' uiAccess='false'" /PDB:"C:\pyisapie\x64\Release\PyISAPIe.pdb" /SUBSYSTEM:WINDOWS /OPT:REF /OPT:ICF /PGD:"C:\pyisapie\x64\Release\PyISAPIe.pgd" /LTCG /TLBID:1 /DYNAMICBASE:NO /IMPLIB:"x64\Release\PyISAPIe.lib" /MACHINE:X64 /ERRORREPORT:QUEUE

    I am using VS2010 and i checked if python27.lib is accessible and everything seems fine. Can you please help me

  11. geographika says:

    Hi – it has been a while since I did this. I’ve not tried with 2.7, but you probably have to add:

    #elif PYI_PY_VERSION >= PY_27
    #define PYI_PY_VERSION_MAJOR PY_27
    #include #include #include

    My build outout for Python 2.6 (in VS2010) is:

    /OUT:"x64\Release\PyISAPIe.dll" /INCREMENTAL:NO /NOLOGO /LIBPATH:"D:\Projects\PyISAPIe\PyISAPIe\Python\x64\Python26\libs" /LIBPATH:"D:\Projects\PyISAPIe\PyISAPIe\Python\x64\Python25\libs" /DLL "kernel32.lib" "user32.lib" "gdi32.lib" "winspool.lib" "comdlg32.lib" "advapi32.lib" "shell32.lib" "ole32.lib" "oleaut32.lib" "uuid.lib" "odbc32.lib" "odbccp32.lib" /NODEFAULTLIB:"libc libcmt msvcrt" /DEF:"PyISAPIe.def" /MANIFEST /ManifestFile:"x64\Release\PyISAPIe.dll.intermediate.manifest" /ALLOWISOLATION /MANIFESTUAC:"level='asInvoker' uiAccess='false'" /PDB:"D:\Projects\PyISAPIe\PyISAPIe\x64\Release\PyISAPIe.pdb" /SUBSYSTEM:WINDOWS /OPT:REF /OPT:ICF /PGD:"D:\Projects\PyISAPIe\PyISAPIe\x64\Release\PyISAPIe.pgd" /LTCG /TLBID:1 /DYNAMICBASE:NO /IMPLIB:"x64\Release\PyISAPIe.lib" /MACHINE:X64 /ERRORREPORT:QUEUE

Pings to this post

  1. […] geographika » Compiling a 64 bit Version of PyISAPIe […]

  2. […] Install and configure PyISAPIe. You can follow the instructions described on this post or in the README file included with PyISAPIe . If you want to run a 64 bit version, have a look at this post. […]

  3. […] not a compiled version of this available for Python 2.7 (x64 in my case).  geographika has a great post on doing this.  The following instructions are based on his guide, updated with newer versions.  […]

Leave a Reply

Your email address will not be published. Required fields are marked *


You may use these tags : <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>