How to Fix Access Denied Error When Opening Jupyter Notebook in Firefox

Encountering an `Access Denied` error while trying to launch Jupyter Notebook in Firefox? Discover effective solutions to troubleshoot and resolve this issue easily! --- This video is based on the question https://stackoverflow.com/q/64339693/ asked by the user 'Reza Ghari' ( https://stackoverflow.com/u/12989925/ ) and on the answer https://stackoverflow.com/a/64361161/ provided by the user 'Mohammad Fatehi' ( https://stackoverflow.com/u/10883820/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions. Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: jupyter notebook doesn't open: Access Denied Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l... The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license. If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com. --- Troubleshooting Access Denied Error in Jupyter Notebook on Firefox Using Jupyter Notebook is a great way to manage your code and data analysis. However, some users may experience issues when launching Jupyter, like the notorious Access Denied error. In this guide, we'll explore why this might happen, particularly when using Firefox as your default browser and how you can fix it. Background on the Issue Imagine you’re all set to dive into your data analysis tasks using Jupyter Notebook on Ubuntu 20.04 and Anaconda, but instead of the expected interface, you are greeted with a message stating: [[See Video to Reveal this Text or Code Snippet]] This is certainly frustrating, especially since you previously used Google Chrome without any issues. However, fear not! This problem is often related to proxy settings, which we can rectify easily. Analyzing the Cause The Access Denied error usually indicates that your system is attempting to access Jupyter Notebook through a Web Proxy, causing Firefox to be unable to connect to localhost, the default address used by Jupyter for routing requests. The switch from Google Chrome to Firefox may have exposed this issue if proxy settings weren’t initially optimized for this change. Why It Occurs: Proxy Configuration: Firefox may have a configured proxy that conflicts with Jupyter's access to localhost. Browser Settings: Different browsers handle network settings differently, leading to inconsistencies. Solution: Disabling Proxy in Firefox To solve the Access Denied issue, you can disable the proxy settings in Firefox. Follow these simple steps: Step 1: Open Firefox Settings Open your Firefox browser. Click on the three horizontal lines at the top right corner (Menu). Select Options or Preferences from the dropdown menu. Step 2: Navigate to Network Settings Scroll down and click on Network Settings (usually at the bottom of the page). A new window for Connection Settings will pop up. Step 3: Change Proxy Settings In the Connection Settings window, look for the option that says Manual proxy configuration. Optionally, uncheck the box that says Use system proxy settings. Now, either select No proxy or input localhost in the No proxy for section. This ensures connections to local addresses are not routed through the proxy. Click OK to save your changes. Step 4: Relaunch Jupyter Notebook Go back to your terminal where Jupyter is installed. Navigate to your working directory and run the command: [[See Video to Reveal this Text or Code Snippet]] This should now open Firefox without showing the Access Denied error. Conclusion If you’ve followed these steps, you should be able to launch Jupyter Notebook successfully in Firefox without encountering the Access Denied error. It’s important to verify your browser’s proxy settings whenever similar issues arise, especially after switching between different web browsers. Remember, while temporary fixes may offer relief, ensuring your settings are consistent will help prevent recurring issues. Happy coding with Jupyter!