Hi,
the latest commit 5c9f27e upgrades Nextcloud from version 17 to 19. However, a direct upgrade is not supported. Users need to go to 18.0 first.
Therefore, upgrading an existing release of this chart (with default parameters, i.e., Nextcloud 17) will break on upgrade.
There should be documentation that one needs to go to 18.0 first and that this is a manual step.
Workaround after it happened: fix the version number from 19.x to 17.0.9 in html/version.php (which is on the persistent volume). If 19.x is mentioned there, the 18.x upgrade will abort and not even see that the database is still 17.x.