Describe the bug

Relying on axios automatic serialization to create a form-data results in this error. The following lines are responsible of this error : https://github.com/axios/axios/blob/release/dist/node/axios.cjs#L2654 (mainly the getLengthSync function)

According to form-data themselves, using getLengthSync is not recommended.

To Reproduce

• Create a file buffer with fs.createReadStream
• Set HTTP header Content-Type to multipart/form-data to make use of automatic serialization
• Get the form-data Cannot calculate proper length in synchronous way. error

Code snippet

const axios = require("axios");
const fs = require("node:fs");
const fileBuffer = fs.createReadStream("./file.ext");

axios.post('https://httpbin.org/post', {file: fileBuffer}, {
  headers: {
    'Content-Type': 'multipart/form-data'
  }
})
.then(({data}) => console.log(data))
.catch((err) => console.error(err));

Expected behavior

The content length should be calculated without throwing any error.

Axios Version

1.3.0

Adapter Version

No response

Browser

No response

Browser Version

No response

Node.js Version

16.19.0

OS

No response

Additional Library Versions

No response

Additional context/Screenshots

No response