What is "406-Not Acceptable Response" in HTTP?

Question

Your operation did not fail.

Your backend service is saying that the response type it is returning is not provided in the Accept HTTP header in your Client request.

Ref: http://en.wikipedia.org/wiki/List_of_HTTP_header_fields

1. Find out the response (content type) returned by Service.
2. Provide this (content type) in your request Accept header.

http://en.wikipedia.org/wiki/HTTP_status_code -> 406

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.

You mentioned you're using Ruby on Rails as a backend. You didn't post the code for the relevant method, but my guess is that it looks something like this:

def create
  post = Post.create params[:post]
  respond_to do |format|
    format.json { render :json => post }
  end
end

Change it to:

def create
  post = Post.create params[:post])
  render :json => post
end

And it will solve your problem. It worked for me :)

"Sometimes" this can mean that the server had an internal error, and wanted to respond with an error message (ex: 500 with JSON payload) but since the request headers didn't say it accepted JSON, it returns a 406 instead. Go figure. (in this case: spring boot webapp).

In which case, your operation did fail. But the failure message was obscured by another.

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.