Strange 406 Not Acceptable on redirect after update

after record create , the redirect to admins_partners_url is working
fine ( :index displaying the page)
but after the update , the record update is performed , but I get this
error

updated_at = ‘2012-01-18 14:57:08’ WHERE partners.id = 7
(10.1ms) COMMIT
Redirected to http://lvh.me:3000/admins/partners
Completed 406 Not Acceptable

same url… on create and update

def create
@partner = Partner.new(params[:partner])
if @partner.save
flash.now[:notice] = t(:partner_added)
redirect_to admins_partners_url

def update
@partner = Partner.find(params[:id])
respond_to do |format|
if @partner.update_attributes(params[:partner])
flash.now[:notice] = t(:partner_updated)
redirect_to admins_partners_url

I don’t get it …

[SOLVED] sorry for posting too fast … pasting my code , I just
noticed that I had a
respond_to do |format| block in my update code … removing it did
the trick !

I don’t understand yet why … but I’ll do some search about it …