How to Fix ModuleNotFoundError: No module named 'websockets.datastructures' in FastAPI with Uvicorn

Facing the `ModuleNotFoundError` when running a FastAPI server with Uvicorn? Learn how to troubleshoot and fix this error quickly with our step-by-step guide.
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Introduction

Understanding the Problem

Before diving into the solution, it's important to understand why you're encountering this error.

The required package (websockets) is installed but outdated or incompatible.

Your environment (like virtualenv) has not been properly set up with the necessary packages.

There may be issues with the installation of setuptools or pip.

Solution: Update Your Environment

The good news is that this problem can often be resolved with a couple of commands that update your package management tools. Follow the steps below:

Step 1: Update setuptools

setuptools is a package development and distribution library often required in Python projects. To ensure you have the latest version, run this command:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Update pip

Next, it’s important to ensure that your pip, the Python package installer, is up to date. Run the following command:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Reinstall Websockets

Now that your package management tools are updated, it's a good idea to reinstall the websockets package to ensure you have the correct version. You can do this by running:

[[See Video to Reveal this Text or Code Snippet]]

This command forces pip to reinstall the websockets package, ensuring that you are using a compatible version that includes the necessary module.

Verify Your Installation

After completing the steps above, try rerunning your FastAPI application:

[[See Video to Reveal this Text or Code Snippet]]

If the installation is correct, you should no longer see the ModuleNotFoundError.

Conclusion

Encountering a ModuleNotFoundError can be frustrating, especially when you're eager to get your FastAPI application up and running. However, by keeping your setuptools, pip, and websockets package updated, you can resolve these issues with ease.

Don't let dependency issues hold you back from building amazing applications. Happy coding!