POST http://localhost:3000/upload 404 (Not Found) - node.js

Question

I'm working on a file upload app and have run into an issue. When submitting to upload the file, I get a post 404 error in the console. The full code is here. I'm assuming that there's an issue in the file upload component but can't seem to understand the problem here.
FileUpload.js
import React, { useState } from "react";
import axios from "axios";
export const FileUpload = () => {
const [file, setFile] = useState("");
const [filename, setFilename] = useState("Choose File");
const [uploadedFile, setUploadedFile] = useState({});
const onChange = (e) => {
setFile(e.target.files[0]);
setFilename(e.target.files[0].name);
};
const onSubmit = async (e) => {
e.preventDefault();
const formData = new FormData();
formData.append("file", file);
try {
const res = await axios.post("/upload", formData, {
headers: {
"Content-Type": "multipart/form-data",
},
});
const { fileName, filePath } = res.data;
setUploadedFile({ filename, filePath });
} catch (err) {
if (err.response.status === 500) {
console.log("There was a problem with the server");
} else {
console.log(err.response.data.msg);
}
}
};
return (
<>
<form onSubmit={onSubmit}>
<div class="custom-file">
<input
type="file"
class="custom-file-input"
id="customFile"
onChange={onChange}
/>
<label class="custom-file-label" for="customFile">
{filename}
</label>
</div>
<input
type="submit"
value="Upload"
className="btn btn-primary btn-block mt-4"
/>
</form>
</>
);
};