I am attempting to run a flask backend server with flask. Whenever I run:

python3 server.py 

The server hosts and whenever I go to it, it gives an error 404 not found. Here is the code:

from flask import Flask, request, jsonify
from flask_cors import CORS
import subprocess

app = Flask(__name__)
CORS(app)  # Enable CORS for all routes

@app.before_request
def before_request():
    print(f"Request path: {request.path}")

@app.route('/execute-file/', methods=['POST'])
def execute_file():
  try:
    # Get the file name from the request body
    fileName = request.form.get('fileName')
    if not fileName:
      return jsonify({'success': False, 'error': 'File name not provided'})

    # Execute the file
    result = subprocess.run(['python', f'lib/execute/{fileName}'], capture_output=True, text=True)

    if result.returncode == 0:
      return jsonify({'success': True, 'output': result.stdout})
    else:
      return jsonify({'success': False, 'error': result.stderr})
  except Exception as e:
    return jsonify({'success': False, 'error': str(e)})

if __name__ == '__main__':
  app.run(host='0.0.0.0', port=8000)

The error itself says: Not Found The requested URL was not found on the server. If you entered the URL manually please check your spelling and try again. console displays the following:

* Serving Flask app 'server' 
* Debug mode: off WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead. 
* Running on all addresses (0.0.0.0) 
* Running on http://127.0.0.1:8000 
* Running on http://192.168.1.21:8000 
Press CTRL+C to quit 
Request path: / 127.0.0.1 - - [20/Mar/2025 19:11:22] "GET / HTTP/1.1" 404 -

I am attempting to run a flask backend server with flask. Whenever I run:

python3 server.py 

The server hosts and whenever I go to it, it gives an error 404 not found. Here is the code:

from flask import Flask, request, jsonify
from flask_cors import CORS
import subprocess

app = Flask(__name__)
CORS(app)  # Enable CORS for all routes

@app.before_request
def before_request():
    print(f"Request path: {request.path}")

@app.route('/execute-file/', methods=['POST'])
def execute_file():
  try:
    # Get the file name from the request body
    fileName = request.form.get('fileName')
    if not fileName:
      return jsonify({'success': False, 'error': 'File name not provided'})

    # Execute the file
    result = subprocess.run(['python', f'lib/execute/{fileName}'], capture_output=True, text=True)

    if result.returncode == 0:
      return jsonify({'success': True, 'output': result.stdout})
    else:
      return jsonify({'success': False, 'error': result.stderr})
  except Exception as e:
    return jsonify({'success': False, 'error': str(e)})

if __name__ == '__main__':
  app.run(host='0.0.0.0', port=8000)

The error itself says: Not Found The requested URL was not found on the server. If you entered the URL manually please check your spelling and try again. console displays the following:

* Serving Flask app 'server' 
* Debug mode: off WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead. 
* Running on all addresses (0.0.0.0) 
* Running on http://127.0.0.1:8000 
* Running on http://192.168.1.21:8000 
Press CTRL+C to quit 
Request path: / 127.0.0.1 - - [20/Mar/2025 19:11:22] "GET / HTTP/1.1" 404 -

• python
• flask
• http-status-code-404

• You don't have a route for neither / nor GET. – Klaus D. Commented Mar 20 at 14:02

1 Answer 1

If you are accessing 127.0.0.1:8000 through a browser, you need to define a route for / to handle the request.

Define it like this:

@app.route('/', methods=['GET'])
def home():
    return "Hello, world!"

Additionally, if you want to access your currently defined route:

@app.route('/execute-file/', methods=['POST'])
...

you can consider using Postman to conveniently test your API(i.e., set input url as 127.0.0.1:8000/execute-file and set method as POST).