CSRF verification failed. (CSRF cookie when submitting forms)

I am having this error while making a new public position (when the representative is not yet in the data base) using Firefox-ESR 45.9.0:

Forbidden (403)

CSRF verification failed. Request aborted.

You are seeing this message because this site requires a CSRF cookie when submitting forms. This cookie is required for security reasons, to ensure that your browser is not being hijacked by third parties.

If you have configured your browser to disable cookies, please re-enable them, at least for this site, or for 'same-origin' requests.

More information is available with DEBUG=True.

I can reproduce the error from another web browser (TOR with no additional cookie plugin) so it might come from the server but I can't tell.

What I actually tried:

What I got:

I hope it can help if a bug is out there.