Upgrading Docker Instance from v18 to v19

Nextcloud version (eg, 18.0.2):
18.0.4 (from official docker image)

Operating system and version (eg, Ubuntu 20.04):
Ubuntu 18LTS

Apache or nginx version (eg, Apache 2.4.25):
I believe the docker image uses apache

PHP version (eg, 7.1):
7.3.17

The issue you are facing:
I cannot seem to upgrade via php occ upgrade - it states that this is the latest version.

If this is not the way to upgrade NC - Might someone point to the proper way. To reiterate, I’m using the official docker image, which doesn’t seem to be create a named volume, but if this is meant to be a “get the latest image” – what would be the best way to keep the data/configurations?

Is this the first time you’ve seen this error? (Y/N):
Yes - though I’m new to NC

Steps to replicate it:

  1. sudo docker exec -u www-data -it bash
  2. php /var/www/html/occ upgrade

The output of your terminal:

NextCloud is already latest version

The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):

<?php$CONFIG=array('htaccess.RewriteBase'=>'/','memcache.local'=>'\\OC\\Memcache\\APCu','apps_paths'=>array(0=>array('path'=>'/var/www/html/apps','url'=>'/apps','writable'=>false,),1=>array('path'=>'/var/www/html/custom_apps','url'=>'/custom_apps','writable'=>true,),),'instanceid'=>'ocdplxi5u6vx','passwordsalt'=>'saak5jVwBUSYvREs2F+J/yk4gnQu4B','secret'=>'2OI/s9JL7ykVeHREcoaN/azJXfjaJ7S4V4oYxCT2eFLmTzeE','trusted_domains'=>array(0=>'cloud.essenceofzen.org:8080',),'trusted_proxies'=>array(0=>'cloud.essenceofzen.org',),'datadirectory'=>'/var/www/html/data','dbtype'=>'mysql','version'=>'18.0.4.2','overwrite.cli.url'=>'cloud.essenceofzen.org','dbname'=>'cloud','dbhost'=>'134.209.32.123:3306','dbport'=>'','dbtableprefix'=>'oc_','mysql.utf8mb4'=>true,'dbuser'=>'oc_admin1','dbpassword'=>'bzFu0+UK9JP4RjXHQINyOIui2TiMNr','installed'=>true,'overwritehost'=>'cloud.essenceofzen.org','overwriteprotocol'=>'https','mail_from_address'=>'cloud','mail_smtpmode'=>'smtp','mail_sendmailmode'=>'smtp','mail_domain'=>'essenceofzen.org','mail_smtpauthtype'=>'LOGIN','mail_smtphost'=>'smtp.zoho.com','mail_smtpauth'=>1,'mail_smtpport'=>'465','mail_smtpname'=>'cloud@essenceofzen.org','mail_smtppassword'=>'We\'reVirtuous3','mail_smtpsecure'=>'ssl','maintenance'=>false,);

The output of your Apache/nginx/system log in /var/log/____: