Persistent 404 NOT_FOUND

[masiraadmiraal-4506]

Persistent 404 NOT_FOUND on Successfully Deployed Serverless Function (Node.js)

Hello Vercel Community,

I’m encountering a very persistent and frustrating issue with a serverless function (api/get-appointment-types.js) in my project, online-afspraken-systeem. Despite repeated successful deployments, the function’s endpoint consistently returns a 404: NOT_FOUND error. I’ve exhausted all troubleshooting steps I can think of, and I’m hoping someone here might have insights.

Project Overview: I’m trying to create a simple Node.js serverless function that acts as an API endpoint, calling an external third-party API (agenda.onlineafspraken.nl/APIREST).

The Problem: After every deployment, the Vercel CLI reports ✅ Production: [URL] and the build logs show “Build Completed” with no critical errors. However, when I try to access the function’s URL, I get a 404: NOT_FOUND error.

Key Troubleshooting Steps Already Taken:

1. Deployment URL Confirmed: I’m using the exact production URL provided by Vercel.
2. vercel.json Configuration: I’ve tried multiple configurations, including specific and catch-all routes, and verified the file path. The current vercel.json is:JSON{ "version": 2, "builds": [ { "src": "api/get-appointment-types.js", "use": "@vercel/node" } ], "routes": [ { "src": "/api/get-appointment-types", "dest": "/api/get-appointment-types.js" } ] }
3. File Location: The get-appointment-types.js file is correctly located in the api/ directory in the root of my project.
4. Environment Variables: ONLINE_AFSPRAKEN_API_KEY and ONLINE_AFSPRAKEN_API_SECRET are correctly set in the Vercel project settings for the Production environment.
5. Build Logs: Consistently show “Build Completed” successfully.
6. Runtime Logs: Unfortunately, since it’s a 404, the function isn’t even invoked, so there are no specific runtime error logs to provide beyond the 404: NOT_FOUND itself.

Most Recent Failing Deployment Details:

• Deployment ID: fra1::jp6fp-1752088431027-1153cc7be122 (this is the most recent I encountered)
• Affected URL: https://online-afspraken-systeem-dnbb3zgku-masiras-projects.vercel.app/api/get-appointment-types

api/get-appointment-types.js Code Content:

`// api/get-appointment-types.js

import axios from ‘axios’;
import CryptoJS from ‘crypto-js’;

export default async function handler(req, res) {
if (req.method !== ‘POST’) {
return res.status(405).json({ error: ‘Method Not Allowed’, message: ‘Only POST requests are accepted.’ });
}

try {
    const ONLINE_AFSPRAKEN_API_KEY = process.env.ONLINE_AFSPRAKEN_API_KEY;
    const ONLINE_AFSPRAKEN_API_SECRET = process.env.ONLINE_AFSPRAKEN_API_SECRET;

    if (!ONLINE_AFSPRAKEN_API_KEY || !ONLINE_AFSPRAKEN_API_SECRET) {
        console.error("Missing API Key or Secret in environment variables.");
        return res.status(500).json({ error: 'Server Configuration Error', message: 'API Key or Secret is missing. Please check Vercel Environment Variables.' });
    }

    const API_URL = "https://agenda.onlineafspraken.nl/APIREST";
    const HTTP_METHOD = "POST";

    const apiSalt = Math.floor(Date.now() / 1000);

    const paramsForSigning = {
        method: "getAppointmentType",
    };

    const sortedKeys = Object.keys(paramsForSigning).sort();
    let stringToSign = "";
    for (const key of sortedKeys) {
        stringToSign += key + paramsForSigning[key];
    }

    stringToSign += ONLINE_AFSPRAKEN_API_SECRET;
    stringToSign += apiSalt.toString();

    const apiSignature = CryptoJS.SHA256(stringToSign).toString();

    const requestBody = new URLSearchParams();
    for (const key in paramsForSigning) {
        if (Object.prototype.hasOwnProperty.call(paramsForSigning, key)) {
            requestBody.append(key, paramsForSigning[key]);
        }
    }
    requestBody.append('api_salt', apiSalt.toString());
    requestBody.append('api_signature', apiSignature);

    const response = await axios.post(API_URL, requestBody.toString(), {
        headers: {
            'Content-Type': 'application/x-www-form-urlencoded',
            'Accept': '*/*',
        },
    });

    res.setHeader('Content-Type', 'application/xml');
    res.status(200).send(response.data);

} catch (error) {
    console.error("Error calling OnlineAfspraken API:", error.message);
    if (error.response) {
        console.error("API Response Data:", error.response.data);
        console.error("API Response Status:", error.response.status);
        console.error("API Response Headers:", error.response.headers);
        res.status(error.response.status).send(error.response.data);
    } else if (error.request) {
        console.error("No response received from API:", error.request);
        res.status(500).json({ error: 'No response from API', message: 'The request was made but no response was received from the OnlineAfspraken API.' });
    } else {
        console.error("Request setup error:", error.message);
        res.status(500).json({ error: 'Internal Server Error', message: 'An unexpected error occurred: ' + error.message });
    }
}

}`

Any help or suggestions from the community would be greatly appreciated! Thank you in advance.

[system]

There’s another community post with 404 debugging tips that might be helpful. Please give these solutions a try and let us know how it goes.

Debugging 404 Errors

Sometimes things don’t go as expected when deploying a website. If you see a 404 on your site, that means the page or resource couldn’t be found. There are many possible causes, and the absence of something can be tricky debug if you don’t know where to look. Here are some things you can do to find the cause and fix it. Debugging Tips Check the error code If you see a mostly white screen with 404: NOT_FOUND along with a Code and and ID then you can click the blue info box below the error deta…

A human should be around soon to offer more advice. But you can also get helpful information quickly by asking v0.

[amyegan]

I see a 500 - FUNCTION_INVOCATION_FAILED error at https://online-afspraken-systeem-dnbb3zgku-masiras-projects.vercel.app/api/get-appointment-types

You should be able to get more details from the runtime logs