OpenCV error: The function is not implemented [Solved]

# OpenCV error: The function is not implemented [Solved]

The OpenCV "error: (-2:Unspecified error) The function is not implemented. Rebuild the library with Windows, GTK+ 2.x or Cocoa support" occurs because of having missing dependencies or opencv-python-headless installed.

To solve the error, uninstall opencv-python-headless and install all missing dependencies.

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OpenCV(4.5.1) C:\Users\bobbyhadz\AppData\Local\Temp\opencv\modules\src\window.cpp:451: error: (-2:Unspecified error) The function is not implemented. Rebuild the library with Windows, GTK+ 2.x or Cocoa support. If you are on Ubuntu or Debian, install libgtk2.0-dev and pkg-config, then re-run cmake or configure script in function 'cvShowImage'

# Install the prerequisites on Ubuntu

If you are on Ubuntu, install the prerequisites as shown in the error message.

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sudo apt install libgtk2.0-dev pkg-config

# Uninstall the opencv-python-headless module

Make sure you don't have the opencv-python-headless module installed because it causes conflicts with opencv-python.

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# 👇️ Uninstall the package that caused the conflict
pip uninstall opencv-python-headless
pip3 uninstall opencv-python-headless

python -m pip uninstall opencv-python-headless
python3 -m pip uninstall opencv-python-headless

# Reinstall the opencv-python module

Now, uninstall the opencv-python module as well.

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# 👇️ Uninstall opencv-python
pip uninstall opencv-python
pip3 uninstall opencv-python

python -m pip uninstall opencv-python
python3 -m pip uninstall opencv-python

Finally, reinstall opencv-python.

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# 👇️ install opencv-python
pip install opencv-python
pip3 install opencv-python

python -m pip install opencv-python
python3 -m pip install opencv-python

If the error is resolved after reinstalling opencv-python, update your requirements.txt file with the following command.

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pip freeze > requirements.txt

If you got the error in Spyder IDE, try restarting it.

# Update your version of the opencv-python package

If the error persists, try to run the installation command with the --upgrade option.

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pip install opencv-python --upgrade
pip3 install opencv-python --upgrade

python -m pip install opencv-python --upgrade
python3 -m pip install opencv-python --upgrade

The --upgrade option upgrades the specified package to the newest available version.

# Create a virtual environment

If none of the suggestions helped, try creating a virtual environment as you might have clashing versions of the opencv-python, opencv-python-headless and opencv-contrib-python packages installed.

1. Create a virtual environment.
2. Activate the virtual environment.
3. Run the pip install command with the virtual environment active.

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# 👇️ Use the correct version of Python when creating VENV
python -m venv venv

# 👇️ Activate on Unix or MacOS
source venv/bin/activate

# 👇️ Activate on Windows (cmd.exe)
venv\Scripts\activate.bat

# 👇️ Activate on Windows (PowerShell)
venv\Scripts\Activate.ps1

# 👇️ Install the specific package in the virtual environment
pip install opencv-python

If the python -m venv venv command doesn't work, try the following 2 commands:

• python3 -m venv venv
• py -m venv venv

Your virtual environment will use the version of Python that was used to create it.

If the error is resolved after installing opencv-python in a virtual environment, update your requirements.txt file with the following command.

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pip freeze > requirements.txt

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

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