Upgraded from ZC version 1.3.9h to 1.5.5f and imported old database into a new one. PHP version 7.1.24. Site URL is http://fishid.com/zenstore5

Adding books to the cart, registering as a user, clicking forgot password or even using the contact us page results in "Whoops! Your session has expired".

I noticed that any action after the initial page adds an extra "/" after the domain name, could this be part of the problem?