Now, visit the index page using your browser: To stop the server, use CTRL+C, but don’t do that just yet. In a production environment, displaying detailed errors exposes your application to security vulnerabilities. The debug mode is off, which means that the Flask debugger is not running, and you won’t receive helpful error messages in your application.
Flask 404 not found how to#
You can also check out this Flask deployment tutorial with Gunicorn, or this one with uWSGI, or you can use DigitalOcean App Platform to deploy your Flask application by following the How To Deploy a Flask App Using Gunicorn to App Platform tutorial. You’re using this server for development, so you can ignore this warning, but for more information, see the Deployment Options page on the Flask documentation. The warning message stresses that this server is not for a production deployment.
The environment, which is production here. The Flask application being served ( app.py in this case).
This output provides the following information: Do not use it in a production deployment. Output * Serving Flask app 'app' (lazy loading)
Flask 404 not found code#
With your programming environment activated and Flask installed, open a file called app.py for editing inside your flask_app directory:Īdd the following code inside the app.py file: Then you’ll run it with debug mode on and use the debugger to troubleshoot application errors. In this step, you’ll create an application that has a few errors and run it without debug mode to see how the application responds. You can review our How To Build a Website with HTML tutorial series for background knowledge. If you are not familiar with Flask, check out How to Create Your First Web Application Using Flask and Python and How to Use Templates in a Flask Application.Īn understanding of basic HTML concepts. In this tutorial we’ll call our project directory flask_app.Īn understanding of basic Flask concepts, such as routes, view functions, and templates.
Flask 404 not found install#
You can follow the tutorial for your distribution in How To Install and Set Up a Local Programming Environment for Python 3 series.
PrerequisitesĪ local Python 3 programming environment. You’ll create custom error pages, use the Flask debugger to troubleshoot exceptions, and use logging to track events in your application. In this tutorial, you’ll build a small web application that demonstrates how to handle common errors one encounters when developing a web application. You’ll find it easier and smoother to develop your Flask applications if you learn how to handle errors and exceptions properly. You might misspell a variable, misuse a for loop, or construct an if statement in a way that raises a Python exception, like calling a function before declaring it, or simply looking for a page that doesn’t exist. When you’re developing a web application, you will inevitably run into situations where your application behaves in a way contrary to what you expected. Introductionįlask is a lightweight Python web framework that provides useful tools and features for creating web applications in the Python Language. The author selected the Free and Open Source Fund to receive a donation as part of the Write for DOnations program.
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