Hi,
I just activated and configured Paypal and Stripe modules for payments.
I also enabled, in Settings/PDF, the flag to add into the invoice the payment link but when the link is generated the ref value is missing and the page shown says “Wrong parameters - ref” .
The invoice is Convalidated.
I have similar issue, in version18.0.3. After validation of the invoice, the payment link created for Strip works fine, but the embedded url in the pdf invoice has the the same “Bad parameters - ref”, the url stops at ref. there is nothing beyond that like invoice number etc as is in the payment lin.
I have tried several time PHP 8 and the payment link is incomplete. Same process I repeated with PHP 7.4. It worked all the time. the payment link printed on the PDF is complete and works! It could be the compatibility or Database Driver. I am using Maria Data base, which is fully compatible to Mysql.So try yourself rolling back to PHP 7.4