ModuleNotFoundError: No module named 'flask' in Python

# ModuleNotFoundError: No module named 'flask' in Python

The Python "ModuleNotFoundError: No module named 'flask'" occurs when we forget to install the Flask module before importing it or install it in an incorrect environment.

To solve the error, install the module by running the pip install Flask command.

Open your terminal in your project's root directory and install the flask module.

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# 👇️ In a virtual environment or using Python 2
pip install Flask

# 👇️ For Python 3 (could also be pip3.10 depending on your version)
pip3 install Flask

# 👇️ If you get a permissions error
sudo pip3 install Flask
pip install Flask --user

# 👇️ If you don't have pip in your PATH environment variable
python -m pip install Flask

# 👇️ For Python 3 (could also be pip3.10 depending on your version)
python3 -m pip install Flask

# 👇️ Using py alias (Windows)
py -m pip install Flask

# 👇️ For Anaconda
conda install -c anaconda flask

# 👇️ For Jupyter Notebook
!pip install Flask

After you install the Flask package, try importing it like:

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from flask import Flask

print(dir(Flask))

The error occurs for multiple reasons:

1. Not having the Flask package installed by running pip install Flask.
2. Installing the package in a different Python version than the one you're using.
3. Installing the package globally and not in your virtual environment.
4. Your IDE running an incorrect version of Python.
5. Naming your module flask.py which would shadow the official module.
6. Declaring a variable named flask which would shadow the imported variable.

# Install the package in a Virtual Environment

If you are using a virtual environment, make sure you are installing Flask in your virtual environment and not globally.

You can try creating a virtual environment if you don't already have one.

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# 👇️ Optionally update your requirements.txt file
pip freeze > requirements.txt

# 👇️ Deactivate your virtual environment (if you have one active)
deactivate

# 👇️ Remove the old virtual environment folder: macOS and Linux
rm -rf venv

# 👇️ Remove the old virtual environment folder: Windows
rd /s /q "venv"

# 👇️ 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 Flask in your virtual environment
pip install Flask

# 👇️ Install the modules in your requirements.txt file
# (Only needed this if you have a requirements.txt file)
pip install -r requirements.txt

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 persists, get your Python version and make sure you are installing the package using the correct Python version.

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python --version

For example, my Python version is 3.10.4, so I would install the Flask package with pip3.10 install Flask.

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pip3.10 install Flask

# 👇️ If you get a permissions error use pip3 (NOT pip3.X)
sudo pip3 install Flask

Notice that the version number corresponds to the version of pip I'm using.

If the PATH for pip is not set up on your machine, replace pip with python3 -m pip:

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# 👇️ Make sure to use your version of Python, e.g. 3.10
python3 -m pip install Flask

If the "No module named 'flask'" error persists, try restarting your IDE and development server/script.

# Check if the package is installed

You can check if you have the Flask package installed by running the pip show Flask command.

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# 👇️ Check if you have Flask installed
pip show Flask

# 👇️ If you don't have pip set up in PATH
python -m pip show Flask

The pip show Flask command will either state that the package is not installed or show a bunch of information about the package, including the location where the package is installed.

# Make sure your IDE is using the correct Python version

If the package is not installed, make sure your IDE is using the correct version of Python.

For example, In VSCode, you can press CTRL + Shift + P or (⌘ + Shift + P on Mac) to open the command palette.

Then type "Python select interpreter" in the field.

Then Select the correct Python version from the dropdown menu.

Your IDE should be using the same version of Python (including the virtual environment) that you are using to install packages from your terminal.

You also shouldn't be declaring a variable named flask as that would also shadow the original module.

# Try reinstalling the package

If the error is not resolved, try to uninstall the Flask package and then reinstall it.

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# 👇️ Check if you have Flask installed
pip show Flask

# 👇️ If you don't have pip set up in PATH
python -m pip show Flask

# 👇️ Uninstall Flask
pip uninstall Flask

# 👇️ If you don't have pip set up in PATH
python -m pip uninstall Flask

# 👇️ Install Flask
pip install Flask

# 👇️ If you don't have pip set up in PATH
python -m pip install Flask

Try restarting your IDE and development server/script.

You can also try to upgrade the version of the Flask package.

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pip install Flask --upgrade

# 👇️ If you don't have pip set up in PATH
python -m pip install Flask --upgrade

# Import "flask" could not be resolved from source Pylance

The error "Import "flask" could not be resolved from source Pylance" occurs when the flask module is not installed or you have selected the incorrect Python interpreter in your IDE (e.g. Visual Studio Code).

To solve the error, install flask and select the correct Python interpreter in your IDE.

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Import "flask" could not be resolved from source Pylance(reportMissingModuleSource) [Ln 1, Col 8]

# Make sure the correct Python interpreter is selected in your IDE

If you have multiple Python versions installed on your machine, you might have installed the flask package using the incorrect version or your IDE might be set up to use a different version.

For example, In Visual Studio Code you can:

1. Press CTRL + Shift + P or (⌘ + Shift + P on macOS) to open the command palette.

Then type "Python select interpreter" in the search field.

2. Select the correct Python version from the dropdown menu.

If the error persists, try restarting your IDE and development server/script. VSCode often glitches and a reboot resolves the issue.

If the error is not resolved, try to use the Visual Studio Code terminal to install the flask module.

You can press CTRL + ` (Backtick) on your keyboard to open the Visual Studio code terminal.

Once you open the terminal, Visual Studio Code will automatically activate your virtual environment (if you have one).

Run the pip install flask command.

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pip install flask

If the error persists, try to select the Python interpreter by specifying the path:

1. Press CTRL + Shift + P or (⌘ + Shift + P on Mac) to open the command palette.
2. Type "Python select interpreter" in the field.

3. Select "Enter interpreter path...".

4. Click on "Find".

5. In the window that opens, navigate to your Python executable:

• If you have a virtual environment on Windows, click on your venv folder, then double-click on the Scripts folder, select the python.exe file and then Select interpreter.

• If you have a virtual environment on macOS or Linux, click on your venv folder, then double-click on the bin folder, select the python file and then Select interpreter.

• If you don't have a virtual environment, use one of the following commands to get your path to your python.exe or python executable, specify the path to the file and select the executable.

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where python

python -c "import sys; print(sys.executable)"

If the error persists, try restarting your IDE and development server/script.

# Alternatively, use a comment to disable the warning

If none of the suggestions helped, you can use a comment to disable the Pylance warning in your IDE.

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import flask  # type: ignore

print(flask)

You simply have to add the # type: ignore command on the same line as the import statement to disable the check for the specific import.

# Table of Contents

1. Install Flask on Windows
2. Install Flask on macOS or Linux
3. Install Flask in Visual Studio Code
4. Install Flask in PyCharm
5. Install Flask in Anaconda
6. Install Flask in Jupyter Notebook

# Install Flask on Windows

To install the Flask module on Windows:

1. Type CMD in the search bar and open the Command Prompt application.
2. Type pip install flask and press Enter.

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pip install flask

# 👇️ For Python 3
pip3 install flask

# 👇️ If you don't have pip in your PATH environment variable
python -m pip install flask

# 👇️ For Python 3
python3 -m pip install flask

# 👇️ Using py alias
py -m pip install flask

# 👇️ If you get a permissions error
pip install flask --user

# 👇️ For Anaconda
conda install -c anaconda flask

If the command doesn't succeed, try running CMD as an administrator.

If you get the error 'pip' is not recognized as an internal or external command, use the python -m command when installing flask.

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python -m pip install flask

python3 -m pip install flask

py -m pip install flask

Alternatively, you can install the flask module in a virtual environment:

1. Open the root directory of your project.
2. Press Shift and right-click in Explorer.

3. Click on "Open PowerShell window here".
4. Run the following commands.

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# 👇️ Might also be: "python3 -m venv venv"
python -m venv venv

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

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

# 👇️ Install Flask in your virtual environment
pip install flask

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

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

If you see an error message that ps1 cannot be loaded because running scripts is disabled on this system, run the following command, type "yes" when prompted and rerun the activation command.

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Set-ExecutionPolicy RemoteSigned -Scope CurrentUser

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pip show flask
pip3 show flask

python -m pip show flask
python3 -m pip show flask

The pip show flask command will either state that the package is not installed or show a bunch of information about the package, including the location where the package is installed.

# Install Flask on macOS or Linux

To install Flask on macOS or Linux:

1. Search for "terminal" and start the application.
2. Type pip install flask and press Enter.

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pip install flask

# 👇️ For Python 3
pip3 install flask

# 👇️ If you get a permissions error
sudo pip3 install flask

# 👇️ If you don't have pip in your PATH environment variable
python -m pip install flask

# 👇️ For Python 3
python3 -m pip install flask

# 👇️ Alternative if you get a permissions error
pip install flask --user

# 👇️ For Anaconda
conda install -c anaconda flask

If you get an error that pip isn't found, use the python -m command.

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python -m pip install flask

python3 -m pip install flask

If you get a permissions error, prefix the command with sudo.

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sudo pip install flask

sudo pip3 install flask

Alternatively, you can install the flask package in a virtual environment:

1. Open your terminal in the root directory of your project.
2. Run the following commands.

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# 👇️ Could also be "python -m venv venv"
python3 -m venv venv

# 👇️ Activate virtual env on macOS or Linux
source venv/bin/activate

# 👇️ Install Flask in your virtual environment
pip install flask

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

You can use the pip show command to verify flask has been installed successfully.

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pip show flask
pip3 show flask

python -m pip show flask
python3 -m pip show flask

The pip show flask command will either state that the package is not installed or show a bunch of information about the package.

# Install Flask in Visual Studio Code

To install Flask in Visual Studio Code:

1. Press CTRL + ` (Backtick) on your keyboard to open the terminal.
2. Run the pip install flask command to install the flask module.

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pip install flask

# 👇️ For Python 3
pip3 install flask

# 👇️ If you get a permissions error
sudo pip3 install flask

# 👇️ If you don't have pip in your PATH environment variable
python -m pip install flask

# 👇️ For Python 3
python3 -m pip install flask

# 👇️ Using py alias
py -m pip install flask

# 👇️ Alternative if you get a permissions error
pip install flask --user

When installing Python modules in Visual Studio code, make sure that your IDE is configured to use the correct Python version.

Press CTRL+Shift+P or (⌘ + Shift + P on Mac) to open the command palette.

Then type "Python select interpreter" in the field.

Then Select the correct Python version from the dropdown menu.

You can use the python --version command if you need to get your version of Python.

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python --version
python3 --version

You can also try creating a virtual environment if you don't already have one.

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# 👇️ Could also be "python -m venv venv" or "py -m venv venv"
python3 -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 Flask in your virtual environment
pip install flask

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

# Install Flask in PyCharm

To install Flask in PyCharm:

1. Press Alt+F12 on your keyboard to open the terminal.
2. Run the pip install flask command to install the flask module.

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pip install flask

# 👇️ For Python 3
pip3 install flask

# 👇️ If you get a permissions error
sudo pip3 install flask

# 👇️ If you don't have pip in your PATH environment variable
python -m pip install flask

# 👇️ For Python 3
python3 -m pip install flask

# 👇️ Using py alias
py -m pip install flask

# 👇️ Alternative if you get a permissions error
pip install flask --user

Alternatively, you can use the IDE itself to install the module.

1. Click on "File" > "Settings" > "Project" > "Python Interpreter".
2. Click on the + icon and type Flask.
3. Click on "Install Package".

Click on "File" > "Settings" > "Project" > "Python Interpreter".

Then Select the correct Python version from the dropdown menu.

You can use the python --version command if you need to get your version of Python.

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python --version
python3 --version

# Install Flask in Anaconda

To install Flask in Anaconda:

1. Open your Anaconda Navigator.
2. Click on "Environments" and select your project.
3. Type flask in the search bar to the right.
4. Tick the flask package and click on "Apply".

Alternatively, you can install the flask package with a command.

If you are on Windows, search for "Anaconda Prompt" and open the application.

If you are on macOS or Linux, open your terminal.

Run the following command to install the flask package.

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# 👇️ Using conda
conda install -c anaconda flask

# 👇️ Alternatively use `pip`
pip install flask

# 👇️ For Python 3
pip3 install flask

# 👇️ If you get a permissions error
sudo pip3 install flask

# 👇️ If you don't have pip in your PATH environment variable
python -m pip install flask

# 👇️ For Python 3
python3 -m pip install flask

# 👇️ Using py alias
py -m pip install flask

# 👇️ Alternative if you get a permissions error
pip install flask --user

Click on the following article if you need to install a specific version of the package using Anaconda.

# Install Flask in Jupyter Notebook

To install Flask in Jupyter Notebook:

1. Open your terminal and type "jupyter notebook".

2. Click on "New" and then "Terminal" in the browser tab.

3. Type pip install flask and press Enter.

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# 👇️ Using pip
pip install flask

# 👇️ For Python 3
pip3 install flask

# 👇️ If you get a permissions error
sudo pip3 install flask

# 👇️ If you don't have pip in your PATH environment variable
python -m pip install flask

# 👇️ For Python 3
python3 -m pip install flask

# 👇️ Using py alias
py -m pip install flask

# 👇️ Using conda
conda install -c anaconda flask

# 👇️ Alternative if you get a permissions error
pip install flask --user

Alternatively, you can use the Python ipykernel.

1. Open your terminal and type "jupyter notebook".

2. Click on "New" and then click on "Python 3 (ipykernel)".

3. Type !pip install flask and click on "Run".

Note that the pip install command must be prefixed with an exclamation mark if you use this approach.

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!pip install flask

Once you type the command, click "Run" to install the flask module.

If you get a permissions error, e.g. "[WinError: 5] Access is denied", add the --user option to the installation command.

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!pip install flask --user

If the error persists, try to restart the Jupyter Kernel and rerun the command.