almost always when i try to install stuff it says that the package doesnt have a release file and that because updating from such a repository cant be done securely its disabled by default
this is the output when i do apt-get update:
https://pastebin.com/dfWZQLz8
and also when i try to install an os update the button in the software center does nothing
but with discover i can install system updates
It seems that you have upgraded to 18.10 (cosmic), which will be supported 9 months.
I can recommend to backup you data and then reinstall 18.04 LTS to live without problems for next 5 years.
If you still want to stay on 18.10 then disable PPAs with
sudo add-apt-repository -r ppa:alexlarsson/flatpak
sudo add-apt-repository -r ppa:screenlets/ppa
and then run sudo apt-get update followed by sudo apt-get dist-upgrade (to get new dependencies) and so on.
i just installed ubuntu mate on my desktop for the first time, my previous experience was on raspberry pi and i downloaded this version because i thought why not try the unstable version
so hsould i remove all ppas?
You should indeed remove the ones that don’t have a cosmic (18.10) version yet, as they break APT. You can also try to set them back to “bionic” (18.04) if they have this version. If the packages they provide don’t have dependencies that are specific to 18.10, they should work just as well.
EDIT: after checking, while alexlarsson/flatpak does have a bionic PPA, screenlets has yakkety (16.10) at most. You can try it but if you don’t really need screenlets, it would be better to just drop it.
Flatpak is in the cosmic repos, presumably in a newer version than the bionic PPA but screenlets isn’t.
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i just wanted to try folderview because i liked fences
My commands above will not remove packages from the system.
They simply comment deb / deb-src but packages from them will remain.
The proper way to remove a PPA is to use ppa-purge, it’ll disable it and revert the packages it contains to the version from the repos.
Though, if you’ve just added them improperly (in the way that they don’t have a cosmic version) after installing Ubuntu 18.10, you can just disable/delete them as you didn’t install anything from them.
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I know this proper way with ppa-purge.
For current situation I have chosen add-apt-repository -r to save installed packages.