Fix “ModuleNotFoundError: No module named ‘plotly'” in Python – Even after pip install

When trying to use the plotly data visualization library in Python, you might encounter the following error that stops your script:

ModuleNotFoundError: No module named 'plotly'

"Wait, I just ran pip install plotly!" "It says Requirement already satisfied, but it still won't work!"

If you are facing this situation, you are not alone. While this error can mean you simply forgot to install it, in many cases, it means the place where you installed it and the place where you are running it are different.

In this article, we will explain the real cause of this error and how to fix it for different environments.

Conclusion: Why does this error occur?

Here is the conclusion. 90% of the time, the cause is this:

The Python you used with pip and the Python running your code are different.

You likely have multiple versions of Python installed on your PC, and:

• You ran pip install on Python A.
• You ran import plotly on Python B.

This "mismatch" is very common, especially if you use VS Code, Anaconda, or Jupyter Notebook.

1. The Basics: Check Installation

If you haven't installed it at all yet, simply installing it will fix it.

Run in Terminal (Command Prompt)

pip install plotly

If you need to specify Python 3 on Mac or Linux:

pip3 install plotly

After installation, run the following code. If no error appears, you are good to go.

import plotly
print("plotly is installed")

If this doesn't fix it, read on.

2. Error persists even after "pip install"

If you get Requirement already satisfied but still see ModuleNotFoundError when running your script, it is an environment mismatch.

How to check: Verify Python and pip paths

Run these commands in your terminal to compare the paths.

Mac / Linux:

which python
which pip

Windows:

where python
where pip

If these two paths point to completely different folders, that's the cause. For example, "pip is installing to Anaconda's Python, but you are running the standard Python."

The Fix

The most reliable way is to specify the full path of the Python executable you want to use.

# Example: Install to the Python that the 'python' command refers to
python -m pip install plotly

By typing python -m pip, you ensure that pip runs for "the exact Python that runs when you type python".

3. Error in VS Code

In VS Code, you can select the Python Interpreter from the bottom right of the screen (or Command Palette).

1. Press Ctrl + Shift + P (Mac: Cmd + Shift + P).
2. Type Python: Select Interpreter and select it.
3. Choose the Python environment where you installed plotly.

A common trap is installing it globally, but VS Code is using a virtual environment (venv) it created automatically.

4. Error in Jupyter Notebook

Jupyter Notebook (or JupyterLab) often runs on a kernel independent of your terminal. "I ran pip install in the terminal but it doesn't work in Notebook" is caused by this.

The Fix: Install inside a Notebook Cell

The most reliable method is to run the installation command inside a Notebook cell.

import sys
!{sys.executable} -m pip install plotly

If you just write !pip install plotly, it might use a different pip than the one the Notebook kernel is using. Using {sys.executable} forces the installation into "the exact Python running this Notebook".

5. Forgot to Activate Virtual Environment (venv)

If you use venv for your projects, forgetting to activate it will make your shell use the global environment.

Windows:

.\venv\Scripts\activate
pip install plotly

Mac / Linux:

source venv/bin/activate
pip install plotly

Make sure you see (venv) at the beginning of your terminal line before installing.

Summary

If you see ModuleNotFoundError: No module named 'plotly', don't panic. Check these steps:

1. Run pip install plotly first.
2. If that fails, run python -m pip install plotly.
3. In VS Code, check the selected Interpreter.
4. In Jupyter, run !{sys.executable} -m pip ….

When "it should be there but it's not," suspecting "where did I put it?" is the shortcut to the solution.