I'm trying to send orders to a third-party after and ONLY after an order has been paid and has now been set to 'Processing' as status. What's the best observer to use to set up this to work for all payments types?
After reading several sources it seems like:
checkout_onepage_controller_success_action. This can be used if your order payment is success. There is another event
sales_order_payment_capture. It may also use in your case. I didn't use it before.
Check this LINK
As per discussion, it seems that
sales_order_invoice_pay is the perfect observer for capturing order paid and that event is still available in Magento 1.9. (not deprecated)
For more reference, check out this Link