File Metadata Microservice - Test 4 fails with "blob is not implemented yet" in dom-test-evaluator.js

danish_butt · August 7, 2026, 1:35pm

My solution is fully functional and verified working (tested manually and via headless Chromium/Puppeteer, including a real cross-origin fetch() identical to how the test likely runs):

Solution URL: https://file-metadata-microservice-abc.vercel.app

Test 1, 2, 3 pass. Test 4 fails:
“When you submit a file, you receive the file name, type, and size in bytes within the JSON response.”

I opened DevTools Console while running the test and found the actual error is happening
inside freeCodeCamp’s own test sandbox, not my app:

Error: blob is not implemented yet
at o (dom-test-evaluator.js:2:102733)
at Object.blob (dom-test-evaluator.js:2:103360)
at eval (eval at #a (dom-test-evaluator.js:2:255755), :6:31)
at async #a (dom-test-evaluator.js:2:255749)
at async DOMTestEvaluator.handleMessage (dom-test-evaluator.js:2:256257)

This matches an existing report: File Metadata Microservice - Bug Report · Issue #65377 · freeCodeCamp/freeCodeCamp · GitHub

Could a moderator help verify my solution or advise how to get this challenge marked complete?
Thanks!

Lesson URL (copy - paste from your browser’s address bar)

ILM · August 7, 2026, 3:23pm

this is archived content, as such it is not maintained

we suggest you move instead to the newly releaded back end v9 certification https://www.freecodecamp.org/learn/back-end-development-and-apis-v9/

angelcrsq · August 7, 2026, 3:33pm

I’ve seen that error come up constantly on the forum. Is it really that complicated to implement a fix that prevents that error? Regardless of whether the course is archived and no longer updated, consideration should be given to those who want to obtain the certificate but are prevented from doing so by this issue.

The people who want to obtain the certificate should be taken into account.

angelcrsq · August 7, 2026, 3:43pm

Someone proposed a solution some time ago.

github.com/freeCodeCamp/freeCodeCamp

File Metadata Microservice - Bug Report

opened 12:35AM - 21 Jan 26 UTC

closed 08:27AM - 13 Feb 26 UTC

yirassssindaba-coder

scope: curriculum status: waiting triage archived coursework

### Describe the Issue The File Metadata Microservice correctly returns the upl…oaded file’s name, MIME type, and size in bytes in a JSON response when tested locally through the upload form and direct API requests. Despite this, the freeCodeCamp testing interface may display “Failed: 4” even though the API response strictly follows the required format. This behavior cannot be reproduced locally and suggests a limitation or inconsistency in the freeCodeCamp testing environment rather than an error in the application logic. The project functions correctly when run locally and matches the official project specifications. ### Affected Page https://github.com/yirassssindaba-coder/File-Metadata-Microservice ### Your code ``` index.js: 'use strict'; require('dotenv').config(); const express = require('express'); const cors = require('cors'); const path = require('path'); const multer = require('multer'); const app = express(); app.use(cors()); app.use('/public', express.static(path.join(process.cwd(), 'public'))); // Home page app.get('/', (req, res) => { res.sendFile(path.join(process.cwd(), 'views', 'index.html')); }); // Multer: memory storage is enough for FCC tests const upload = multer({ storage: multer.memoryStorage() }); // IMPORTANT: field name must be "upfile" app.post('/api/fileanalyse', upload.single('upfile'), (req, res) => { if (!req.file) { // Not required by FCC tests, but prevents server error return res.status(400).json({ error: 'No file uploaded' }); } return res.json({ name: req.file.originalname, type: req.file.mimetype, size: req.file.size }); }); const port = process.env.PORT || 3000; app.listen(port, () => { console.log('Your app is listening on port ' + port); }); module.exports = app; ``` views/index.html: <!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8" /> <meta name="viewport" content="width=device-width, initial-scale=1" /> <title>File Metadata Microservice</title> <link rel="stylesheet" href="/public/style.css" /> </head> <body> <main> <h1>File Metadata Microservice</h1> <p>Upload a file to get its metadata (name, type, size).</p> <form action="/api/fileanalyse" method="post" enctype="multipart/form-data"> <label for="upfile">Choose a file to upload</label> <input id="upfile" type="file" name="upfile" /> <button type="submit">Upload</button> </form> </main> </body> </html> ### Expected behavior When a file is submitted through the upload form, the API should respond with a JSON object containing the file’s original name, MIME type, and size in bytes. Since this behavior can be consistently verified locally and matches the project specification, the freeCodeCamp test labeled “Failed: 4” should pass successfully. ### Screenshots <img width="1909" height="889" alt="Image" src="https://github.com/user-attachments/assets/31e1f964-a1e6-467c-bb14-d4f38be5fb76" /> ### System - Device: [e.g. iPhone 6, Laptop] - OS: [e.g. iOS 14, Windows 10, Ubuntu 20.04] - Browser: [e.g. Chrome, Safari] - Version: [e.g. 22] ### Additional context _No response_

ILM · August 7, 2026, 3:52pm

it is not a matter of how complicated or simple it is, but it has been decided to not dedicate time to the archived content maintenance

you can try to leave feedback, via email or github issue

angelcrsq · August 7, 2026, 3:55pm

The issues I’ve seen regarding this topic are always “closed as not planned”; the point is that there are people who want to finish the course, and this error prevents them from doing so.

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File Metadata Microservice - Test 4 fails with "blob is not implemented yet" in dom-test-evaluator.js

My solution is fully functional and verified working (tested manually and via headless Chromium/Puppeteer, including a real cross-origin fetch() identical to how the test likely runs):

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