Gads, I should have taken notes but a few key things, make sure the entire db is converted to innodb and all tables and columns are utf8mb4_unicode_ci (i had a ton that were mb3, likely due to the age of the forum). I used the manual approach, but still had to refer to the sql backup of the old forum to create a handful of tables that the update claimed were missing. It still took 5 attempts at a manual upgrade as it would time out, but it would pick up where it left off. I also had to restore the uploads folder as some part of the upgrade wiped out 10 years of user photos. Backups are your friend.