I am still cleaning up the aftermath of the upgrade to 12. The base upgrade went well and it seems the issues I have encountered is mostly to the ports.
First off, email and my web server did not work out of the box. I had to reinstall a lot of ports and I did not realize that having OpenSSL port can cause a lot of havoc. Went back to the base OpenSSL and reinstalled the ports.
I also realized that doing a pkg remove will sometimes help with certain conflicts. Portmaster failed several times and I found that its mostly because I was using the OpenSSL port version.