Hello,
I began the update process for my Nextcloud 15.0.8 installation running on a FreeNAS FreeBSD jail.
First I checked my installation integrity. It required a mysql fix.
I followed these instructions which seemed to have worked but did provide some errors upon running the maintenance:repair command at the end. I was forced to exit maintenance mode and then everything seemed fine.
Then, I ran the update which failed. Here is the provided information from the failure:
https://pastebin.com/RqXRRsaY
Thank you for your help!