WARNING: Can't verify CSRF token authenticity rails

Question

I am sending data from view to controller with AJAXand I got this error:

WARNING: Can\'t verify CSRF token authenticity

I think

Answer 1

I'm using Rails 4.2.4 and couldn't work out why I was getting:

Can't verify CSRF token authenticity

I have in the layout:

<%= csrf_meta_tags %>

In the controller:

protect_from_forgery with: :exception

Invoking tcpdump -A -s 999 -i lo port 3000 was showing the header being set ( despite not needing to set the headers with ajaxSetup - it was done already):

X-CSRF-Token: XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
X-Requested-With: XMLHttpRequest
DNT: 1
Content-Length: 125
authenticity_token=XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

In the end it was failing because I had cookies switched off. CSRF doesn't work without cookies being enabled, so this is another possible cause if you're seeing this error.