Develop Reference

Unable to run PythonWin For Python 3.9 64bit

I was trying to create Python executables on Windows 10 Pro (latest) so was upgrading to the latest packages but it's changed.
I've just gotten rid of Python 3.6 and reinstalled Python 3.9. I then went and installed PythonWin for it using the following (there no longer seems to be what was a standard install package):
**pip install pywin32**
Python is on the start menu but, unlike earlier installs, the new way of installing PythonWin this doesn't seem to give me any kind of way to run the program. Surely it should create some kind of shortcut on the start menu?
Any advice on this would be most helpful.
James

SOLVED!
While I still have no idea why a Start Menu shortcut wasn't installed, I have found the executable that runs PythonWin.
It was located in the following folder:
"C:\Users<MyUserID>\AppData\Local\Programs\Python\Python39\Lib\site-packages\pythonwin"
Thanks :)

"DLL load failed" when import cv2 (opencv)

In [windows server 2012 R2 x64, python 3.7 64x]
pip install opencv-contrib-python
installed without any error .
and when I try to import it
import cv2
show me this error :
Traceback (most recent call last):
File "test.py", line 1, in <module>
import cv2
File "C:\Program Files\Python37\lib\site-packages\cv2\__init__.py", line 3, in
<module>
from .cv2 import *
ImportError: DLL load failed: The specified module could not be found.
and I see another topic about this error but their solution does not work for me :
- DLL load failed error when importing cv2
- Failure to import cv2 in python : DLL load failed
- and a lot of pages in here
some of them say about that problem because anaconda, and I don't have anaconda even. and many say that problem 32 or 64 version, I try both and disappointment. many about system variables...
what dll failed to load? cv2? why?
what i try till now:
change python version : 3.5, 3.7, 2.7 in 86x and 64x (uninstall complete last version and delete all remain files in program files ... then install new one)
try with another packages like : opencv-python, opencv-contrib, try install specific versions with .whl (in some topic i read about this so install numpy-1.14.5+mkl-cp37-cp37m-win_amd64.whl and opencv_python-3.4.3+contrib-cp37-cp37m-win_amd64.whl but anything not change)
import numpy before cv2 for every test
installed Microsoft Visual C++ 2015 Redistributable Update 3 , 2008 , 2010 , 2017 for 64x
UPDATE
NEXT 2 DAY
I try to manage missing dll base on dependency walker that mention in bellow post, download all dll and put them in system 32, its a good clue but not solve the problem.
DAY 4,5
my next step , trying compile OpenCV in my machine , install visual studio 2012 + cmake and base on document compile 2 version , 64x and 32 , compiling have a lot of problem itself (like missing some lib from c lang and need to install Visual C++ Redistributable for Visual Studio 2012 ...) and I resolve all of them ,then I have 2 success compiled version but both have the same problem with missing dll, the compile process is so slow and give 2 day from me. so if fail on this mission :/ I search for a new way...
DAY 6
my next step is to try to run OpenCV in my machine with docker ( I try but docker windows just install on windows 10 and windows server 2016) so I search for an alternative. I found Vagrant that work like docker but with VM (visual box) today my time spend for this articles, it's amazing, the concept of docker and vagrant is so Attractive, and I play with this like that I have new puzzle :)
first error show on ... and limitless errors go on :
Day 7
Vagrant tests failed too because my windows server 2012 is a vb machine (visual server) and run a visual box in another visual box impossible!
so I need new clues :
Day 8-9
try install vagrant with VMware , I download VMware, unfortunately this plugin is not free (79$) so I try to work with pythonanywhere.com that 'gives you access to machines with a full Python environment already installed.' in this free account, you can't openurl with urllib , and more limit...
so I wanna try to install ubuntu in VMware my self... I read here results after work. it's Impossible with same reason vb (visual box)

This can happen if you are using windows 10 N distribution, the N distributions does not come pre installed with windows media feature pack, which is required after OpenCV version 3.4 and onwards.
The preferred solution is to install the feature pack at : https://www.microsoft.com/en-us/software-download/mediafeaturepack
Be careful to choose the version that works with your current version of windows.
If that is not an option, fall back to an earlier version of OpenCV that does not have dll dependencies, you can do that by:pip install opencv-python=3.3.0.9
Since windows rolled out it's N version this problem has been seen at many places, and has many impacts across the windows environment, the fastest way to identify if you have this problem is open youtube in Edge browser, if it says HTML5 media plugin not found, this is the problem.
Update May 2020: There is a new way to install media pack for Windows 10 N.
https://support.microsoft.com/en-us/help/4562569/media-feature-pack-for-windows-10-n-may-2020

I had the same error (although I compiled OpenCV myself), in my case there were some DLL dependencies missing. You can check that with the program Dependency Walker.
Download Dependency Walker and run it, and open the file cv2.pyd with Dependency Walker, it should be in C:\Program Files\Python37\lib\site-packages\cv2\ if the pip package installed correctly.
This program then scans for dependencies (which may take a few minutes) and it then shows missing DLL files in red.

I have faced the similar issue in Windows Server 2012 r2. After lot of findings I found that mfplat.dll was missing which is related to Window Media Service.
Hence you have to manually install the features so that you can get dll related to window media service.
Turn windows features on or off
Skip the roles screen and directly go to Feature screen
Select "Desktop Experience" under "User Interfaces and Infrastructure"
After this all required dll of opencv would be available.

Python 3.7 may not support some modules.
Try installing python 3.6.4
Using command prompt, "pip install
opencv" or "pip install opencv-python"
Import cv2

Can you try uninstalling opencv and installing it using a wheel file instead? Here is a website that has many versions of OpenCV compiled for windows, search for the one you need and simply install it with pip command.
So if you have Python 3.6 (64 Bit) and wish to install OpenCV 3.4.3 then download the wheel file:
opencv_python‑3.4.3‑cp36‑cp36m‑win_amd64.whl

I had similar issue except that I'm using Anaconda3 and this code here solved it:
conda install -c anaconda py-OpenCV

After 15 days of brain storming, This solution worked for me. And I am sure that it will work for you too. I installed anaconda to use OpenCV 3.1.0. I followed following Steps:
1) I have installed anaconda-5.3 64-bit installer (614.3 MB) which uses python 3.7. You can download anaconda from link: https://www.anaconda.com/download/#windows
2) After installation of anaconda, open anaconda prompt by typing "anaconda prompt" on windows start button. Open with "Run as administrator".
3) You have to create new environment to install and use OpenCV module.Write following commands to create and activate new environment:
>conda create --name myNewEnv python=3.5.0
>activate myNewEnv
"myNewEnv" is the name of new enviroment.
4)Now you need to install prerequisite for OpenCV, which is numpy and then install opencv3. Start internet before executing following commands:
>conda install numpy
>conda install anaconda-client
>conda install --channel https://conda.anaconda.org/menpo opencv3
5)OpenCV3 has been installed. Now, verify installation by executing following commands:(myNewEnv) C:\Users\Nilesh> python
>>>import cv2
>>>cv2.__version__
Follow steps given below, when you want to start OpenCV3 second time onwards:
1) Open "anaconda command promt" from start menu with "run as administrator" rights
2) Type command >activate your_new_environment_name
3) Assume that you want to run file located on desktop, for that write following command:
> cd C:\Users\Nilesh\Desktop
4) Now your working directory is Desktop.
5) Type following command to run any code (for example test.py).
> python test.py
Note: Here, python means version-3.
I hope this solution will work for you.

I had the same problem on Windows Server 2012 R2 x64. I was creating executable file using PyInstaller and got error in runtime:
ImportError: DLL load failed: The specified module could not be found.
After installing "Visual C++ redistributable" 2015 and enabling "Media Foundation" feature my problem was resolved.
There is more informations in documentation: OpenCV Documentation

I was having this problem on Windows. I resolved this error by checking instructions here.
Q: Import fails on Windows: ImportError: DLL load failed: The specified module could not be found?
A: If the import fails on Windows, make sure you have
Visual C++ redistributable 2015 installed.
If you are using older Windows version than Windows 10 and latest system updates are not installed, Universal C Runtime might be also required.
Windows N and KN editions do not include Media Feature Pack which is required by OpenCV. If you are using Windows N or KN edition, please install also Windows Media Feature Pack

i was suffering from the same problem "DLL load failed" after reading tons of answers and articles i got a solution.
i don't know this works for you or not but give it a try.
tools and versions i used: anaconda - 5.3.1, python - 3.7, win 10 (64 bit)
Steps i performed :
step1:i installed opencv 3.4.4 from here
then extract into C drive (you can do wherever you want)
step2: copy cv2.pyd file from [C:\opencv\build\python\cv2\python-3.7] here to [C:\Users\"user-name"\Anaconda3\Lib\site-packages] here.
step3: run dependency walker to detect which dll files are missing,
after running dependency walker in my case it showed two dll files are not loading, they are (1)OPENCV_WORLD344.DLL and (2)IESHIMS.DLL.
i don't know about your situation but you can do this-> find files name using dependency walker then find their path and follow step4.
step4: open System property->Advanced->Environment variables, now edit path and add C:\opencv\build\x64\vc14\bin (in my case this was the place where OPENCV_WORLD344.DLL is stored) and after doing this, import cv2 in python.
If my answer does not work then add a comment.

It helps me pip install opencv-contrib-python Anaconda Prompt, python 3.7.1 cv2 4.1.1

I was having the same issue. I resolved this error by downgrading open cv.
pip install opencv-python==3.3.0.9

its worked well for me.*
Answer is Need to put cv2.pyd file to your virtual environment.
need to put under two folder of envs,
first is under DLLS folder and
Second is under Lib/site-packages
To get cv2.pyd > download from this link https://sourceforge.net/projects/opencvlibrary/ and then extract the download file
You will get opencv folder, after that go inside opencv folder like Downloads\opencv\build\python\2.7 and go one deeper folder depend on your 32 or 64 window version
Copy cv2.pyd Important **** after copying cv2.pyd file to your envs, you need to rename cv2.pyd to _cv2.pyd

I was having this problem on Windows Server 2008R2 fresh install and took almost a day to resolve, as was trying with many hits and trials finally I found solution somewhere in internet (not stackoverflow)
Installed Windows Media Feature Pack for 2008R2 then installed Server Manager-> Features-> Add Features-> Desktop Experience
Server Manager-> Features-> Add Features-> Desktop Experience
and Ink and Handwriting Services.
Besides check list includes
Visual C++ redistributable 2015
Universal C Runtime
Hopefully its will help save time

Installing Python version 3.6 and then installing opencv with the command:
pip install opencv-python==3.3.0.9 resolved this issue for me

All you need is python 3.6.
I've been looking for solution for last 3 days and my problem was solved when i installed python 3.6.7.
After installing python 3.6 you can simply run pip install opencv-python.
Source: https://www.geeksforgeeks.org/setup-opencv-with-pycharm-environment/

Just ran into this problem of cv2 importable from my conda environment but not through the "same" environment in jupyter. The error I was getting was that it couldn't load the dll.
Additionally, I could not get opencv installed through jupyter, even using:
import sys
!conda install --yes --prefix {sys.prefix} numpy
I checked my path using:
import os
os.path
in both my shell and jupyter. They were the same(!).
I was finally able to get things working by running the command:
conda install nb_conda
in my conda environment, as outlined here: https://github.com/udacity/P1_Facial_Keypoints/issues/13
This was eye opening as it created a new install of jupyter note books associated with my env instead of anaconda, with five(!) environments to choose from when creating a page. There were three that seemed to be associated with my conda environment. Interestingly, now it only shows the one named environment as an option when creatin a new notebook again in jupyter (the one associated with the env), but it successfully imports cv2.
For a good read on why this is happening with jupyter:
https://jakevdp.github.io/blog/2017/12/05/installing-python-packages-from-jupyter/

Came here from Windows 10N, upgraded to Windows 11. Had to install Media Feature Pack under Settings -> Apps -> Optional Features -> Add an optional feature.
Windows settings

DLL load failed error when importing cv2

I have installed opencv on my windows machine using python 3.6 without any issues, using:
pip install opencv-python
but when I try to import cv2 I get the following error
ImportError: DLL load failed: The specified module could not be found.
I have seen this post
It says cv2 doesn't work with python 3 I was wondering if this has been fixed or if there is a way around it

I took a lot of time to solve this error!
Run command
pip install opencv-contrib-python

You can download the latest OpenCV 3.2.0 for Python 3.6 on Windows 32-bit or 64-bit machine, look for file starts withopencv_python‑3.2.0‑cp36‑cp36m, from this unofficial site. Then type below command to install it:
pip install opencv_python‑3.2.0‑cp36‑cp36m‑win32.whl (32-bit version)
pip install opencv_python‑3.2.0‑cp36‑cp36m‑win_amd64.whl (64-bit version)
I think it would be easier.
Update on 2017-09-15:
OpenCV 3.3.0 wheel files are now available in the unofficial site and replaced OpenCV 3.2.0.
Update on 2018-02-15:
OpenCV 3.4.0 wheel files are now available in the unofficial site and replaced OpenCV 3.3.0.
Update on 2018-06-19:
OpenCV 3.4.1 wheel files are now available in the unofficial site with CPython 3.5/3.6/3.7 support, and replaced OpenCV 3.4.0.
Update on 2018-10-03:
OpenCV 3.4.3 wheel files are now available in the unofficial site with CPython 3.5/3.6/3.7 support, and replaced OpenCV 3.4.1.
Update on 2019-01-30:
OpenCV 4.0.1 wheel files are now available in the unofficial site with CPython 3.5/3.6/3.7 support.
Update on 2019-06-10:
OpenCV 3.4.6 and OpenCV 4.1.0 wheel files are now available in the unofficial site with CPython 3.5/3.6/3.7 support.
Update on 2023-02-11:
OpenCV 4.5.5 wheel files are now available in the unofficial site with CPython 3.7/3.8/3.9/3.10/3.11 support.

If you are using Anaconda with python 3.5, this is a problem in the Anaconda release. (Refer this issue)
You can fix this issue by copying python3.dll file to Anaconda3 folder (where python.exe is located)
How to get "python3.dll"
In cmd, type python --version to find whether your installation is 64-bit or 32-bit
download python 3.x embeddable zip file from here
Extract the zip file and copy python3.dll file to Anaconda3 folder
But if you can move to Anaconda with python 3.6 you will not face this issue. If it is possible for you, then it is the recommended way..

Recently I have faced the similar issue in Azure Windows Server 2012 r2 . Tried all option with and without Anaconda but none of them helped. After lot of findings I found that mfplat.dll was missing which is related to Window Media Service.
Hence you have to manually install the features so that you can get dll related to window media service.
1.Turn windows features on or off
2.Skip the roles screen and directly go to Feature screen
3.Select "Desktop Experience" under "User Interfaces and Infrastructure"
After this all required dll of media services for opencv would be available.
So if you are planning to run your code in cloud(Window Server) then please dont forget to select Desktop Experience feature.

I ran into this problem on Windows 10 (N) with a new Anaconda installation based on Python 3.7 (OpenCV version 4.0). None of the above advice helped (such as installing OpenCV from the unofficial site nor installing VC Redistributable).
I checked DLL dependencies of ...\AppData\Local\conda\conda\envs\foo\Lib\site-packages\cv2\cv2.cp37-win_amd64.pyd using dumpbin.exe according to this github issue. I noticed a library MF.dll, which I figured out belongs to Windows Media Foundation.
So I installed Media Feature Pack for N versions of Windows 10 and voilà, the issue was resolved!

After spending too much time on this issue and trying out all different answers, here is what found:
The accepted answer by #thewaywewere is no longer applicable. I think this was applicable when opencv-python module still wasn't available.
This is indeed a bug in Anaconda 4.2 because they forgot to ship python3.dll. They have fixed this in next releases but unfortunately 4.2 is the last release with Python 3.5 as default. If you are stuck with Python 3.5 (for example VS2015 is only aware of versions up to 3.5) then you must manually download python3.dll as described in answer by #Ramesh-X.
If you can move on to Python 3.6 (which at present bit difficult if you are using OpenCV and VS2015) then just install latest Anaconda version and you don't have to deal with any of these.

There are many questions on that and many suggestions. None of them helped me for the recent Opencv 3.4.16 and Python 3.6/3.7.
Finally I switched to Pyhon 2.7.15 and installed opencv 3.1.0. The DLL-problem was solved.
When I look in cv2.pyd with dependency walker, the 3.1 has no dependency to one missing dll. Opencv 3.4 has this missing dependency to this dll:
API-MS-WIN-DOWNLEVEL-SHLWAPI-L1-1-0.DLL
may be this is the problem.
P.S.: I have Win7 pofessional 64Bit, 32Bit Python 2.7.15

Frankly there are a lot of very smart and complicated answers here. Mine is dumb and simple. I deleted my conda environment, re-installed from scratch, taking pains to install opencv first. This fixed my problems. Environments are meant to be temporary and diaphanous -- don't get too attached.
So if my environment was called fubar first make sure every instance is deactivated (including any IDEs that are using it). Then remove it:
conda remove --name fubar --all
Now I simply recreate my environment and add opencv first:
conda create --name fubar
conda activate fubar
conda install opencv
And then go from there. First open python and make sure import cv2 works. Then you should be on your way. Note I always (always) install Spyder last as it tends to screw things up when I don't.
Note, if that doesn't work, we have had some cases where people have to uninstall and reinstall Anaconda, and then things worked. Obviously a last resort.

In my case a major update of Windows 10 removed some Windows packages, so other methods (reinstalling opencv etc.) did not help. To fix it, install:
a) Microsoft Visual C++ Redistributable for Visual Studio 2015, 2017 and 2019
b) Media Feature Pack for N versions - needed only if you have Windows 10 N
Both need restart of PC.

I had the same issue when installing opencv 2.4.13 on Anaconda3 (Python 3.6)... I managed to fix this issue by reverting to Anaconda2 (Python 2.7)

this happens because the compiler or the interpreter is finding more than one package of the file, delete all the number of same package you have and then keep only one and then try to install. It serves

The issue is due to the missing python3.dll file in Anaconda3.
To fix the issue, you should simply copy the python3.dll to C:\Program Files\Anaconda3 (or wherever your Anaconda3 is installed).
You can get the python3.dll by downloading the binaries provided at the bottom of the Python's Release page and extracting the python3.dll from the ZIP file.

I had the same issue with python 3.6(Anaconda3) and OpenCV 3.4.1 for spyder to work. Even after copying cv2.pyd into Anaconda3 Users/home/Anaconda3/Lib/site-packages, it didn't work.
But found a solution
Later I installed OpenCV and Dlib on Anaconda and copied the generated cv2.cp36-win_amd64.pyd and dlib.cp36-win_amd64.pyd into Anaconda3 Users/home/Anaconda3/Lib/site-packages. These can be copied from environment folder C:\Users\home\Anaconda3\envs\opencv\Lib\site-packages.
Finally spyder started to work

I managed to get it to work by installing python 3.9.12 in a new environment (using conda), and then installing opencv in that environment. Because of my python version, opencv version 4.5.5 was installed instead of version 4.60.
(I had already updated VC2015-2022 and added the python3.dll to PATH; neither of these worked.)

I have the same problem. when I install WinPython programming, and run opencv after copy the cv2.pyd file from my opencv directory, it will be like this: C:\Users.....\Downloads\opencv\build\python\2.7\x64, x64 or x86 is depend on your 32 or 64 bit devices. and paste to C:\Users.....\Downloads\WinPython-64bit-3.5.4.1Qt5\python-3.5.4.amd64\Lib\site-packages, I prefer the previous python 3.5 than 3.6. Because when I "import cv2" installed (python 3.6) it shows directly: "ImportError: DLL load failed: The specified module could not be found"
Then I install python 3.5 and open WinPyhton Command prompt and type "pip install opencv-python".
The command prompt download opencv automatically, it shows the process like this "Successfully installed opencv-python-3.3.0.10"
Finally, I try to run open cv by type "import cv2", it works
i try to type "cv2.version", and shows: '3.3.0'

Under Winpython : the Winpython-64bit-.../python_.../DLLs directory the file cv2.pyd should be renamed to _cv2.pyd

(base) C:\WINDOWS\system32>conda install C:\Users\Todd\Downloads\opencv3-3.1.0-py35_0.tar.bz2
I ran this command from anaconda terminal after I downloaded the version from
https://anaconda.org/menpo/opencv3/files
This is the only way I could get cv2 to work and I tried everything for two days.

If this helps someone, on official python 3.6 windows docker image, to make this thing work I had to copy following libraries from my desktop:
C:\windows\system32
aepic.dll
avicap32.dll
avifil32.dll
avrt.dll
Chakra.dll
CompPkgSup.dll
CoreUIComponents.dll
cryptngc.dll
dcomp.dll
devmgr.dll
dmenterprisediagnostics.dll
dsreg.dll
edgeIso.dll
edpauditapi.dll
edputil.dll
efsadu.dll
efswrt.dll
ELSCore.dll
evr.dll
ieframe.dll
ksuser.dll
mf.dll
mfasfsrcsnk.dll
mfcore.dll
mfnetcore.dll
mfnetsrc.dll
mfplat.dll
mfreadwrite.dll
mftranscode.dll
msacm32.dll
msacm32.drv
msvfw32.dll
ngcrecovery.dll
oledlg.dll
policymanager.dll
RTWorkQ.dll
shdocvw.dll
webauthn.dll
WpAXHolder.dll
wuceffects.dll
C:\windows\SysWOW64
aepic.dll
avicap32.dll
avifil32.dll
avrt.dll
Chakra.dll
CompPkgSup.dll
CoreUIComponents.dll
cryptngc.dll
dcomp.dll
devmgr.dll
dsreg.dll
edgeIso.dll
edpauditapi.dll
edputil.dll
efsadu.dll
efswrt.dll
ELSCore.dll
evr.dll
ieframe.dll
ksuser.dll
mfasfsrcsnk.dll
mfcore.dll
mfnetcore.dll
mfnetsrc.dll
mfplat.dll
mfreadwrite.dll
mftranscode.dll
msacm32.dll
msvfw32.dll
oledlg.dll
policymanager.dll
RTWorkQ.dll
shdocvw.dll
webauthn.dll
wuceffects.dll`

Please Remember if you want to install python package/libraries for windows,
you should always consider Python unofficial Binaries
Step 1:
Search for your package, download dependent version 2.7 or 3.6 you can find it under Downloads/your_package_version.whl its called python wheel
Step 2:
Now install using pip,
pip install ~/Downloads/your_packae_ver.whl
this will install without any error.

I had the same problem and spent 3 full days wrestling with it. I tried everything suggested: upgrading pip, updating Visual C++, updating Anaconda, manually downloading files and basically every solution I could find on the web. Here's what finally worked maybe it'll help someone else:
1- I ditched Python 3 and Anaconda-based downloads since I noticed they had several problems and downloaded Python 2.7.16 64-bits instead.
2- Navigated to where Pip was located on my drive (for me the path is C:\Python27\Scripts) highlighted the path by selecting it, and typed "cmd" then enter so the Command Prompt opens on that path (I noticed skipping this usually brings about a couple errors)
3- Updated Pip using python -m pip install --upgrade pip on the CMD (again, skipping this and not updating it didn't let this procedure go through)
4- Downloaded the appropriate Wheel file from https://www.lfd.uci.edu/~gohlke/pythonlibs/#opencv (after trying several the one that worked for me was opencv_python-2.4.13.7-cp27-cp27m-win_amd64.whl) I copy-pasted it to the same folder Pip was in (C:\Python27\Scripts for me) and then installed it through CMD using: pip install opencv_python-2.4.13.7-cp27-cp27m-win_amd64.whl. Always through CMD opened on that path as showed in step 2
5- After step 4 when I imported OpenCV using import cv2 I didn't have the DLL error anymore but an error related to numpy (since I had just installed that version of Python and so Numpy wasn't installed yet). I installed numpy by typing pip install numpy and voilà ! The problem was solved and OpenCV imported correctly.
Hope this helps someone.

In my case, I had to install an older version of openCV (windows 10, Python 3.6.8)
pip install opencv-python==3.3.0.9

This error can be caused by missing the following dll
To have this dll install:
https://www.microsoft.com/en-us/software-download/mediafeaturepack
as already explained above

Running python 3.8.8 from windows 10 powershell from an anaconda 4.10.1 environment I installed opencv with
conda install opencv
I could import opencv no problem when I launched python from the command line.
However, when I tried to run code from inside pydev using the python interpreter for the specific anaconda environment I had activated, pydev couldn't find whichever dll it was looking for when importing opencv.
Setting the following environment variable resolved the issue:
CONDA_DLL_SEARCH_MODIFICATION_ENABLE=1
Source: PyDev/Eclipse not loading _mklinit when run from a Conda environment
Which points to this trouble shooting description for a different library loading issue: https://docs.conda.io/projects/conda/en/latest/user-guide/troubleshooting.html#numpy-mkl-library-load-failed

If you are using a server or docker enviroment without a gui (e.g. Windows Core Server) make sure that you use the headless version of cv2:
pip install opencv-contrib-python-headless

I had the same problem, it seems openCV requires Windows Media Feature pack which is not installed on Windows 10 N by default, please install it using the following link:
https://www.microsoft.com/en-us/software-download/mediafeaturepack

Windows 11 N
This a final fix for the people who don't use anaconda.
simply there are missing DLL files, that's it
download the latest version of
https://sourceforge.net/projects/opencvlibrary/
Then after you extract it search for .dll files and copy all of them and paste into C:\Windows\System32 and approve for replacing.
That's it !

Install python using:
pip install opencv-python(It will take the latest version)
Make sure opencv-python is installed in path(\Python\Python36\Lib\site-packages),
you will find cv2 folder over there.
To check the version of cv2:
import cv2
print(cv2.__version__)

Cannot uninstall python 2.7.10 from windows 10

For some reason I messed up my install in python a while ago and I recently tried to repair the install but I am getting an error saying: "The specified account already exists." I then decided to rerun the install package and instead of repairing it decided to delete python so I clicked uninstall and got the error message saying: "There is a problem with this Windows Installer package. A program required for this install to complete could not be run. Contact your support personnel or package vendor." The only package I installed (if it is a package) was VPython and for some reason that does not open whenever I try opening it so I assumed I messed up the download for that also. I decided to go ahead and delete everything in my C directory that had the keyword Python including the Python27 folder but it still gave me the same error.

i have same problem and i use advanced system optimizer and clean registery and repair python then uninstall and it work for me

I can confirm that this works. Use Ccleaner to fix the registry, then use installer to "Repair" 2.7.10 the installation, then use installer to "Remove" the installation.

How do I install Python 2.7 modules on Windows 64-Bit?

I've been looking around the internet for days now and cannot find a solution to my problem. I've learned all the basics to programming in Python 2.7 and I want to add Pip to my copy of 2.7. I found the link to download the unoffical 64-Bit installer (www.lfd.uci.edu/~gohlke/pythonlibs/), but when I downloaded it and ran it, it said I needed to have Python 2.7 (which I do) and it couldn't find it in the registry. I went to Pip's website and downloaded the official Windows installer and unpacked it using WinRAR.
I then tried opening Command Prompt and changed the directory to where the get-pip.py is located and running get-pip.py install but it says it failed to install.
I am completely lost and really need detailed and clear help. Please answer!

It doesn't matter what kind of machine you have. You can run 32-bit Windows on a 64-bit machine. And you can run 32-bit Python on 64-bit Windows.
If you have 32-bit Python, you need to install 32-bit pip. (Or you need to switch to 64-bit Python.)
From your description, you most likely have 32-bit Python on 64-bit Windows, and tried to use a 64-bit pip.
PS, if you want to install it manually instead of using Gohlke's installer, nobody can help you debug your problem based on "it says it failed to install". It produces a lot more output than that, and without that output, it's impossible to know which of the billion things that could possibly go wrong actually did.
PPS, just installing pip is sufficient to install any pure-Python packages. But if you want to install packages that include C extensions, you will need to set up a compiler (either MSVC, or MinGW/gcc), as explained in the pip documentation.