Two instances on Linux Mint. How to upgrade V3-->V4?

Sonarr version (exact version): 3.0.10.1567
Mono version (if Sonarr is not running on Windows): 6.12.0.200
OS: Linux Mint

I have two instances running. sonarr.service and sonarr4k.service. Everything works as I want it to. I’m not even sure if I would gain something by upgrading (opinions welcome) in my case.

sonarr.service content is

[Unit]
Description=Sonarr Daemon
After=network.target

[Service]
User=andropovox
Group=andropovox
UMask=0002

Type=simple
ExecStart=/usr/bin/mono --debug /usr/lib/sonarr/bin/Sonarr.exe -nobrowser -data=/var/lib/sonarr
TimeoutStopSec=20
KillMode=process
Restart=on-failure

[Install]
WantedBy=multi-user.target

sonarr4k.service content is

[Unit]
Description=Sonarr Daemon
After=network.target

[Service]
User=andropovox
Group=andropovox

Type=simple
ExecStart=/usr/bin/mono --debug /usr/lib/sonarr/bin/Sonarr.exe -nobrowser -data=/home/andropovox/.var/lib/Sonarr4k/
TimeoutStopSec=20
KillMode=process
Restart=on-failure

[Install]
WantedBy=multi-user.target

I have
deb Index of /ubuntu/ focal main
in Software Sources, under /etc/apt/sources.list.d/sonarr.list

Sonarr’s website states:

The Sonarr v4 package overwrites v3’s systemd unit if present. It’s advisable to make a backup of the v3 data first and uninstall the previous sonarr package.

I have done backups through System/Backups of both instances. What is the suggested route here?
Ideally, I would prefer to update my existing installations instead of having to redo everything from scratch.
If you uninstall everything, how can existing data be migrated? I find the instructions provided to be quite insufficient for a non-expert user such as myself.

Thanks to anyone kind enough to help.

Added a question mark to the title. With it missing it could have been interpreted as a guide… :slight_smile:

Anyone? Pretty please? Begging for help here, I dread nuking my current installation…

Sonarr’s app data is not removed when you uninstall.

High level: Remove v3, install v4, update ExecStart in both system.d files to point to Sonarr v4’s executable (default system.d file should be updated automatically).

Thanks a lot. Apparently, crossing fingers, all went well.