Pihole didn't update, tried to fix it, without success so far

[galgenfisch]

The issue I am facing:
As my pihole (Raspberry) didn't run Updates for a while I tried to run

pihole -up

I received an error message with the advice to run

sudo get update

The result was:
Ign:1 http://repository.nymea.io buster InRelease
Ign:2 Index of /experimental-silo buster InRelease
Hit:3 Index of /raspbian buster InRelease
Err:4 http://repository.nymea.io buster Release
404 Not Found [IP: 92.205.59.180 80]
Err:5 Index of /experimental-silo buster Release
404 Not Found [IP: 92.205.59.180 80]
Hit:6 Index of /debian buster InRelease
Reading package lists... Done
E: The repository 'http://repository.nymea.io buster Release' no lon
ger has a Release file.
N: Updating from such a repository can't be done securely, and is th
erefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user config
uration details.
E: The repository 'Index of /experimental-silo buster
Release' no longer has a Release file.
N: Updating from such a repository can't be done securely, and is th
erefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user config
uration details.

After some research I found this thread

https://discourse.pi-hole.net/t/unable-to-update-pi-hole-error-web-admin-repo-is-missing-from-system/41599

and did what was suggested there, unfortunately without success.

After that I tried

pihole -r
/usr/local/bin/pihole: line 87: /etc/.pihole/automated install/basic
-install.sh: No such file or directory

and then again

pihole -up
/opt/pihole/update.sh: line 26: /etc/.pihole/automated install/basic
-install.sh: No such file or directory
/opt/pihole/update.sh: line 108: : No such file or directory
/opt/pihole/update.sh: line 111: package_manager_detect: command not
found
/opt/pihole/update.sh: line 112: install_dependent_packages: command
not found
/opt/pihole/update.sh: line 115: is_repo: command not found

Error: Core Pi-hole repo is missing from system!
Please re-run install script from https://pi-hole.net

Unfortunately I don't know how to go on, fix the problem or even to re-run the install script.

Details about my system:

My debug token is:

https://tricorder.pi-hole.net/0yEhafkt/

What I have changed since installing Pi-hole:

Some updates.

Hope someone can help and look forward to your reply.

Thanks in advance!

[rdwebdesign]

This is not a Pi-hole issue. This is an OS level issue.

The command sudo get update is failing.
You are using a repository that longer supports your Operating System:

The repository 'http://repository.nymea.io buster Release' no longer has a Release file.

You need to fix the OS issue before install or update Pi-hole.

Note:
Debian 10 (Buster) is an old OS, not supported by Pi-hole.
My suggestion is to install a new OS and try again.

[galgenfisch]

Thank you for your answer. I will try a complete new installation. My actual pihole was set up by a friend some time ago. Seems it's time to get closer to it, read, learn and install it on my own.