Now Sumup is acting up again: customers are not redirected to the confirmation page. This results in double or triple payments. This often goes unnoticed because customers then switch to a different payment method. I had to pay back several hundred francs today. That's really crap!
I have now deactivated SumUp and quickly created my own module with the Universal Payment Module: when the order is completed, the confirmation page contains a link to a reusable payment link where the customer has to enter the amount manually. It's a bit more complicated, but it's the only reliable, quick solution. Then I don't have to worry about Presta 8, as SumUp still has nothing for that.