Here are details on the testing of 20.0.0beta4 update process to rc2.
Here is updater.log
Error I received during update process:
Create backup
Could not copy "/data/nextcloud/apps/dashboard/js/dashboard.js.map" to "/data/nextcloud/data/updater-ochxgtum9iy3/backups/nextcloud-20.0.0.6/apps/dashboard/js/dashboard.js.map"
Now I’m seeing:
It looks like you are trying to reinstall your Nextcloud. However the file CAN_INSTALL is missing from your config directory. Please create the file CAN_INSTALL in your config folder to continue.
And Nextcloud tries to re-install itself if I manually touch CAN_INSTALL && chmod www-data:www-data CAN_INSTALL
from …/config directory.
/var/www/nextcloud/data# ls
Talkbridge index.html nextcloud.log updater.log
appdata_ochxgtum9iy3 ncp nextcloud.log.1
audit.log ncp-update-backups tmp
files_external news updater-ochxgtum9iy3