Updating packages stopped

[Roman]

Hello everyone,
Some time a perfect updating process stopped working. Instead it generates the following message:

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Install Updates Error log
===========================
Install Updates could not fetch the package cache information lists.
Go to https://www.linuxliteos.com/forums/ and paste the log below into a new or existing thread for assistance.

============ Log ===========

Hit:1 http://dl.google.com/linux/chrome/deb stable InRelease
Ign:2 http://ppa.launchpad.net/daniel.pavel/solaar/ubuntu focal InRelease
Hit:3 http://us.archive.ubuntu.com/ubuntu focal InRelease
Hit:4 http://repo.linuxliteos.com/linuxlite emerald InRelease
Err:5 http://ppa.launchpad.net/daniel.pavel/solaar/ubuntu focal Release
  404  Not Found [IP: 91.189.95.85 80]
Hit:6 http://archive.canonical.com/ubuntu focal InRelease
Hit:7 http://security.ubuntu.com/ubuntu focal-security InRelease
Hit:8 http://us.archive.ubuntu.com/ubuntu focal-updates InRelease
Hit:9 http://us.archive.ubuntu.com/ubuntu focal-backports InRelease
Reading package lists...
E: The repository 'http://ppa.launchpad.net/daniel.pavel/solaar/ubuntu focal Release' does not have a Release file.

===========================
I'd appreciate your help in any form; links, suggestions, etc....
R