Restore Data to New NCP Build

Have been struggling to upgrade my NCP system that had been running well 
for years. Issue was, I was not upgrading as the time went by. 
In preparation for a major upgrade of hardware and software, I read auto 
upgrade and backup options and strategies for moving forward once the major
upgrade was complete.

Had read best way for multiple version number upgrades (from NC14) was to 
do a fresh install and then restore data to that.

My plan was to do a full backup on my my rather loaded (approx 200+GB) 
old version on a Pi3 with a 1TB seagate... then get a fresh install of NCP 
(NC v20 using btrfs) on a new RPi4 with a 1TB SSD. Then to restore my data
but could not find how to restore just the data to a fresh build. 
If restore my full backup.. it just ran over my fresh NCP.
 
I read about how to upgrade a single version at a time and proceeded to go 
from NC14 to NC20 which was relatively quick. Unfortunately, my calendar 
(which was sizeable) broke in the upgrades.... wrong format? After trying to
reinstall the calendar app, I also lost my contact app and now the app store
does not display all of what it used to. I was able to find how to rollback 
apps but at this point things were pretty knackered so  decided to regroup 
and look for help.

Did digging around on /media/USBdrive and found ncdata which has all files 
etc, organized by user. Virtually all of my content was loaded by me as the old
"admin" and hence is under the admin folder. The new NCP builds use "ncp" as the default 
administrative account.

I read about "scan" to register files in the system and thought this might 
be a way to get my data added into a fresh build. Would lose comments on 
data but guessing they are gone regardless. When try to scan a test file I put under the 
/admin/files folder get an unknown user error?

Looking for conceptual sequence of steps to do a fresh build and then 
restore my sizeable data given the scenario outlined above.

=============================
NextCloudPi version v1.35.0
NextCloudPi image NextCloudPi_11-27-20
distribution Debian GNU/Linux 10 \n \l
automount yes
USB devices sda
datadir /media/myCloudDrive/ncdata
data in SD no
data filesystem btrfs
data disk usage 422G/932G
rootfs usage 2.4G/15G
swapfile /var/swap
dbdir /var/lib/mysql
Nextcloud check ok
Nextcloud version 20.0.2.2
HTTPD service up
PHP service up
MariaDB service up
Redis service up
Postfix service up
internet check ok
port check 80 open
port check 443 open
IP REMOVED SENSITIVE VALUE
gateway REMOVED SENSITIVE VALUE
interface eth0
certificates REMOVED SENSITIVE VALUE
NAT loopback no
uptime 13:50

Nope, ncp does not support skipping NC versions. You have to update 1 major version to the next.

Using nc-restore on fresh install will restore NC to the version at which the backup was taken.
You could try to manually update NC version by version using nc-update-nc, or

  • export/download all exportable data like contacts & appointments.
  • Recreate users in a fresh install
  • Put files in ncdata dir path and run nc-scan
  • import contacts calanders etc