[Json] What is “406-Not Acceptable Response” in HTTP?


406 Not Acceptable The resource identified by the request is only capable of generating response entities which have content characteristics not acceptable according to the accept headers sent in the request.

406 happens when the server cannot respond with the accept-header specified in the request. In your case it seems application/json for the response may not be acceptable to the server.


In my Ruby on Rails application I tried to upload an image through the POSTMAN REST client in Base64 format. When I POST the image I am getting a 406 Not Acceptable Response. When I checked my database, the image was there and was successfully saved.

What is the reason for this error, is there anything I need to specify in my header?

My request:

URL --- http://localhost:3000/exercises.json


Content-Type  -  application/json

Raw data:

    "exercise": {
        "subbodypart_ids": [
        "name": "Exercise14"
    "image_file_name": "Pressurebar Above.jpg",
    "image":"******base64 Format*******"

You can also receive a 406 response when invalid cookies are stored or referenced in the browser - for example, when running a Rails server in Dev mode locally.

If you happened to run two different projects on the same port, the browser might reference a cookie from a different localhost session.

This has happened to me...tripped me up for a minute. Looking in browser > Developer Mode > Network showed it.

const request = require('request');

const headers = {
    'Accept': '*/*',
    'User-Agent': 'request',

const options = {
    url: "https://example.com/users/6",
    headers:  headers

request.get(options, (error, response, body) => {