Hello,
I'm sorry but if you have the message
A plugin cancelled the creation/update of the order without displaying any error message.
It really means that there is a plugin which do not authorize the order creation and HikaShop do not have any possibility or knowledge to know which plugin is doing that.
And if a plugin do not authorize the order creation ; the order creation is cancelled.
Now, in all plugins we provide in HikaShop ; we made sure that each time an order created is refused, we display a message to the customer ; so we think it's not an official HikaShop plugin.
Regards,