WindowsError when importing openslide using 64-bit version

[macmatt22]

Context

Issue type (bug report perhaps?):
Operating system (Windows 10):
Platform (64-bit):
OpenSlide version (2016-7-17 64 bit release):
Slide format (NA):

Details

Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
    File "C:\dev_res\python\python2_713\lib\site-packages\openslide\__init__.py", line 29, in <module>
        from openslide import lowlevel
    File "C:\dev_res\python\python2_713\lib\site-packages\openslide\lowlevel.py", line 41, in <module>
        _lib = cdll.LoadLibrary('libopenslide-0.dll')
    File "C:\dev_res\python\python2_713\lib\ctypes\__init__.py", line 440, in LoadLibrary
        return self._dlltype(name)
    File "C:\dev_res\python\python2_713\lib\ctypes\__init__.py", line 362, in __init__
        self._handle = _dlopen(self._name, mode)
WindowsError: [Error 127] The specified procedure could not be found'

I installed the OpenSlide binaries and added the bin folder to my system path. I then installed python-openslide using pip. I tried same workflow with Python 3.5.3 and encountered the same problem. Interestingly, when I tested this with the 32-bit version of Python(2.7)/OpenSlide I did not have this issue. However, I have a 64-bit machine and would prefer to use the 64-bit versions.

Not sure if this is a bug or is specific to my configuration. Any help would be greatly appreciated!

[bgilbert]

Hi @macmatt22, we've received a user report that this error is caused by another copy of one of OpenSlide's dependencies, such as zlib1.dll, in the search path.

[macmatt22]

Thanks for your help! Yeah, it turns out that for at least zlib1.dll there were multiple copies installed by other applications. As the user report stated, I was able to fix the problem by starting python inside the openslide/bin directory - this changes the search hierarchy such that the openslide version of zlib1.dll is found first. For the benefit of a future reader, I added the following to lowlevel.py to allow it to work outside of openslide/bin:

os.environ['PATH'] = "path-to-openslide-bin" + ";" + os.environ['PATH']

Of course with replacing path-to-openslide-bin with the appropriate path and importing os module. This puts the directory of the dll's at the front of the search path.

[jxu]

The issue is that the file is named zlib1.dll instead of something more specific like zlib1-2-11.dll

PS C:\Users\jxu\Downloads\openslide-win64-20171122\openslide-win64-20171122\bin> (Get-Item .\zlib1.dll).versionInfo

ProductVersion   FileVersion      FileName
--------------   -----------      --------
1.2.11           1.2.11           C:\Users\jxu\Downloads\openslide-win64-20171122\opensl...

And OpenSlide finds the wrong DLL

>>> from ctypes.util import find_library
>>> find_library("zlib1")
'C:\\Program Files\\Intel\\WiFi\\bin\\zlib1.dll'

[NourEddy]

I tried to add os.environ['PATH'] = "path-to-openslide-bin" + ";" + os.environ['PATH'], it works perfectly when I use python with Consol, but when I spyder i get the same error as befor can someone help me?

[LiesMH]

I have a similar error. I installed openslide-python with pip and added the path to environment variables, but when I try to import openslide, this error occurs:

FileNotFoundError: Could not find module 'libopenslide-0.dll' (or one of its dependencies). Try using the full path with constructor syntax.

I have tried to add os.environ['PATH'] = "path-to-openslide-bin" + ";" + os.environ['PATH'] to lowlevel.py and to start Python from the openslide bin, but that doesn't help. I also uninstalled openslide several times and tried with different downloads.

Any ideas?

[mallyagirish]

@LiesMH
Maybe you've figured it out already, but I have been facing the same issue and simply adding that line to lowlevel.py didn't work for me either. But I finally got it working after seeing this comment. That is, after ensuring I had the path to the openslide bin folder added to PATH, I only needed to change the line in lowlevel.py that loads the 'libopenslide-0.dll' to the following.

_lib = cdll.LoadLibrary(ctypes.util.find_library("libopenslide-0.dll"))

[jalilahmed]

OS: Windows 10
Python: Anaconda, Python 3.8.5
I think the problem is with the library 'zlib1.dll'. I tried to run find_library(libopenslide-0) and it located the library perfectly fine. But even with addition of os['PATH'] = path-to-openslide-bin" + ";" + os.environ['PATH'] the location for the zlib1.dll is Intel\WiFI\bin.
I solved the issue by adding, the following lines to the lowlevel.py file in , site-packages/openslide/
import os
os.add_dll_directory('PATH_TO_MY_OPENSLIDE_BINARY')

[narminGhaffari]

I am facing the same problem while trying to import openslide package.
my question is, the openslide folder inside the site-packages, I dont have any "bin" folder, Can some one help me with this issue?

[jalilahmed]

@narminGhaffari You are looking at the wrong location. If you go through the installation guide of openslide-python on https://pypi.org/project/openslide-python/ . You first have to Install Openslide. For windows, that means extracting the binaries provided at https://openslide.org/download/. In that folder you will find the /bin/ folder which you have to provide in the PATH variable in environment variables. I hope it solves your issue.

[narminGhaffari]

@jalilahmed thank you alot for the respond. I downloaded the openslide and added this line to the enviroment path and also as every body recomended I added this line os.environ['PATH'] = r"C:\openslide-win64-20171122\openslide-win64-20171122\bin" + ";" + os.environ['PATH'] to the lowlevel.py file.

but unfortunatly I am still receieving the winError 126. I sthere any thing else which I have to do?