[Python] Flask: Getting error 404 on one route specifically

I'm trying to use Flask as the backend to make a small desktop app using Electron and I've hit a weird snag.

Essentially, I have a route, "/appendToList/<some_value>" that should be called via a fetch request from the JavaScript code. It just takes the passed value, which should be a string, and then appends the string to a list for later use.

The route looks like this:

routes.py:

list_o_details:list[str]=[]
@app.route("/appendToList/<some_value>", methods=["POST"])
def appendToList(some_value):
list_o_details.append(some_value)
return {"value":f"Appended {some_value}"}


Running it through Electron gives two errors in the console:


These errors also appear in the terminal, but only after I open the desktop app's console.

If I run the Flask file separately, and try calling the route with curl, it produces the same error 404:



This is weird because my file contains two other routes, both of which work perfectly fine. Below is the entire file:

from flask import Flask
app = Flask(__name__)

list_o_details:list[str]=[]
list_o_sums:list[int]=[]

@app.route("/", methods=["GET","POST"])
def check():
return {"result":"Server active!"}

@app.route("/add/<num1>/<num2>", methods=["POST"])
def addNumbers(num1,num2):
num1=int(num1)
num2=int(num2)
sum = num1+num2
list_o_sums.append(sum)
return {"sum":f"{num1}+{num2}={sum}"}

@app.route("/appendToList/<some_value>", methods=["POST"])
def appendToList(some_value):
list_o_details.append(some_value)
return {"value":f"Appended {some_value}"}

print(app.url_map)

if __name__ == "__main__":
app.run(debug=True)




As you can see, my code includes print(app.url_map) which shows the following:



Though I don't know why it's printed twice, it does show that the URL of "/appedToList/<some_value>" is recognized.

After some testing, I found that if I make a copy of addNumbers() with only one argument like:

@app.route("/adding/<num1>", methods=["POST"])
def addingNumbers(num1):
num1=int(num1)
num2=12
sum = num1+num2
list_o_sums.append(sum)
return {"sum":f"{num1}+{num2}={sum}"}


It also results in the same error:



So, thinking that the number of params was somehow the issue, I changed appendToList() to look like:

@app.route('/appendToList/<some_value>/<placeholder>', methods=["POST"])
def appendToList(some_value,placeholder):
list_o_details.append(some_value)
return {"value":f"Appended {some_value}"}


But the errors persisted.

I don't know what's wrong. The route exists, meaning that this is likely some syntax error within the route itself, but I cannot figure out what that may be. Does anyone know what's going on and how to fix this?

Thanks in advance

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