It might help to explain what PIM Core was. I did a quick search and just found a web site consisting entirely of meaningless marketing blurb (https://pimcore.com/en)
Howard Miller
Beiträge von Howard Miller
I've never used it, but isn't that what the optional plugin 'Sharing Cart' does?
https://moodle.org/plugins/block_sharing_cart
https://moodle.org/plugins/block_sharing_cart
Just to be clear... I meant DO NOT use the database for sessions 
Memcached is a bit "old school". If you have a choice, use Redis. I would definitely switch to a proper cache (for caching, obviously I hope) and for sessions if you have the option. Do it anyway!
Memcached is a bit "old school". If you have a choice, use Redis. I would definitely switch to a proper cache (for caching, obviously I hope) and for sessions if you have the option. Do it anyway!
Just a random thought - you've not set up database sessions have you?
It's a slight over-simplification but - here's were Docker wins - to obtain a new version of Moodle and update all the requirements, copy the config files, change the version numbers and rebuild. In fact, you can have multiple versions of everything running at once. To me, that's what makes it worth the trouble.