...Nothing to do.
When I click in "pay now" I always get redirection to:
Your browser sent a request that this server could not understand.
Reason: You're speaking plain HTTP to an SSL-enabled server port.
Instead use the HTTPS scheme to access this URL, please.
Changing manually the http for https works. My ispconfig is on port 8080 and I use ssl certificate (self-signed).
Is the get_ispconfig_url function working correctly??