Install Update Error 404 ppa release file not found

[Şerban S.]

Please, read the manual:

https://www.linuxliteos.com/manual/software.html#ppa

You need to disable the PPA:

https://ppa.launchpadcontent.net/micahflee/ppa/ubuntu

The Error message is clear enough: The software you want, for whatever reason, lacks the appropriate packages for the OS version.
Uncheck the PPA box, then refresh the sources list.
After that, close the Software & Updates window than restart the update procedure (in CLI, Ctrl+Alt+T):

Code:

sudo apt upgrade