Hi,
That would indicate that :
- a payment was made somehow with that VM IPN URL and then it failed as VM was not found.
- since HikaShop doesn't give such IPN URL to PayPal, but its own, I can only think that there is a problem with the setup of the merchant account were you can enter the IPN URL you want. So please check on that.
- If later you didn't get the orders confirmed, it could be because you deactivated the IPN in the merchant account. You do not it active so that PayPal can notify HikaShop when a payment is made.
And yes, you can enter the IPN URL of HikaShop to PayPal, but normally, it shouldn't be necessary as HikaShop already provides it to PayPal automatically unless you turned off the corresponding setting in the PayPal payment method. so you might want to check the settings of your PayPal payment method in HikaShop.