Failed update - nothing but "Access denied"

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I’m running NextCloud in a jail on TrueNas.
I attempted to run an update to NextCloud from v25 to v27 using the jail update process, and now I only see “Access denied.” on a white screen when I connect to the nextcloud webpage.

Nextcloud version: 25
Operating system and version: FreeBSD 13.1
Apache or nginx version: ?
PHP version: ?

The issue you are facing:
In the detailed NGNIX log, I also see “unable to open primary script: /usr/local/www/nextcloud/index.php”