TypeError: Cannot read property 'length' of undefined when using FormData

[mr-rodgers]

I'm trying to follow the FormData example from the readme. Here's my code:

let form = new FormData();
form.append("username", "username");
form.append("_password", "password");
return fetch(url.format(urlParts), { method: "POST",  body: form });

But I get this error:

TypeError: Cannot read property 'length' of undefined
    at C:\Users\...\node_modules\node-fetch\index.js:97:113
    at new Fetch (C:\Users\...\node_modules\node-fetch\index.js:49:9)
    at Fetch (C:\Users\...\node_modules\node-fetch\index.js:37:10)
    at Promise.resolve.then.then.then (C:\Users\...\migrate.js:78:20)
    at process._tickCallback (internal/process/next_tick.js:103:7)

[yatsyk]

please check #167
previous version of form-data should be ok. you can install it with command:
npm i form-data@1.0.1 --save

[bitinn]

Fixed in node-fetch 1.6.3, note that you need form-data 2.1.0 as well.