How do you send FormData with Axios?

Question

I tried the following from Node.js:

import axios from 'axios';

const axiosInstance = axios.create({});

(async () => {
    const sendData = new FormData();
    sendData.append('firmware', 'hello');

    const result = await axiosInstance({
        data: sendData,
        headers: { 'content-type': 'multipart/form-data' },
        method: 'PUT',
        url: 'http://localhost',
    });

    console.log(result);
})().catch(console.error);

But I got this error when calling send:

AxiosError: Data after transformation must be a string, an ArrayBuffer, a Buffer, or a Stream

I am using axios version ^0.27.2. I tried various ways of stringifying the data, but I kept getting this error. I also tried using the form-data package, but its API does not match the actual FormData API and the data would not actually get sent.

How can I properly send my file as part of a FormData object to my endpoint?

[email protected] is from April 2022. Is there a reason why you need to use such an old version? — robertklep
– robertklep, Commented Jul 28 at 18:12
@robertklep I didn't realize it was old. I will try the latest version. — nullromo
– nullromo, Commented Jul 28 at 18:59
@RuanMendes I have read that thread up and down, but the solution there was just to construct the object differently, which does not work. I'll see if the newer version fixes the problem. — nullromo
– nullromo, Commented Jul 28 at 19:00

traynor · Accepted Answer · 2025-07-28 19:08:42Z

1

Using form-data package, try:

const result = await axiosInstance({
    data: sendData.getBuffer(),
    headers: sendData.getHeaders(),
    method: 'PUT',
    url: 'http://localhost',
});

see:

Return the full formdata request package, as a Buffer. You can insert this Buffer in e.g. Axios to send multipart data.
axios.post('https://example.com/path/to/api', form.getBuffer(), form.getHeaders());
Note: Because the output is of type Buffer, you can only append types that are accepted by Buffer: string, Buffer, ArrayBuffer, Array, or Array-like Object. A ReadStream for example will result in an error.

Buffer getBuffer()

edited Jul 28 at 19:08

answered Jul 28 at 19:05

traynor

10.4k3 gold badges15 silver badges30 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

nullromo Jul 28 at 19:08

getBuffer() is not an instance method for FormData. It appears this is something made up by the form-data package.

traynor Jul 28 at 19:13

@nullromo true, but they don't claim to be spec compliant..

nullromo · Accepted Answer · 2025-07-28 23:05:16Z

0

As @robertklep pointed out, my axios version was old. Updating to the latest (currently ^1.11.0) solved my problem.

answered Jul 28 at 23:05

nullromo

2,7374 gold badges25 silver badges55 bronze badges

Collectives™ on Stack Overflow

How do you send FormData with Axios?

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related