Apt repo add with human error, empty AppCenter

Question

I installed Elementary OS since 2 weeks now, and I wanted to install Syncthing, what I did... But I went to this page and due to my window width, I typed 2 commands instead of one :

echo "deb https://apt.syncthing.net/ syncthing stable" | sudo tee /etc/apt/sources.list

and

sudo tee /etc/apt/sources.list/syncthing.list

Or something like that, I don't remember precisely. Then I typed the entire command without error :

echo "deb https://apt.syncthing.net/ syncthing stable" | sudo tee /etc/apt/sources.list.d/syncthing.list

This didn't prevented me to install Syncthing. But after that, I had a error message from the appcenter telling me that it wasn't able to update its database, since then I can only see the installed apps in the AppCenter and install some that it already had in memory in the suggestion category. The error message doesn't appears anymore, because the AppCenter, even after multiple uninstall (with apt purge) reboot and reinstall, doesn't have anymore the little spinning round which normally indicates it is looking for updates or some software corresponding to what you typed in the research field.

I also saw these issues report here and there but it didn't solve my problem.

So my computer is still usable but I can't do any update or searching/installing software via the AppCenter anymore.

Also,it is strange there is no such OS update that I was used to with the AppCenter when I do it with:

or

Each day I normally have a new software update, I think because juno is young. And here no update since two days! Moreover, if this problem get fixed with an update, I will not be able to do this update. As you can see I learn Italian, I'm french and I am writing in English; please excuse me for language issues.

Thank you for reading me until here, if somebody has an idea.

Answer 1

Open Files as administrator (Right click on the icon> New Window as Admin) and navigate to /etc/apt/ . Check the file sources.list and compare with this one. If it has the same entries then it's fine.

# deb cdrom:[elementary OS 5.0 _Juno_ - Stable amd64 (20181016)]/ bionic contrib main non-free

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://es.archive.ubuntu.com/ubuntu/ bionic main restricted
# deb-src http://es.archive.ubuntu.com/ubuntu/ bionic main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://es.archive.ubuntu.com/ubuntu/ bionic-updates main restricted
# deb-src http://es.archive.ubuntu.com/ubuntu/ bionic-updates main restricted

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://es.archive.ubuntu.com/ubuntu/ bionic universe
# deb-src http://es.archive.ubuntu.com/ubuntu/ bionic universe
deb http://es.archive.ubuntu.com/ubuntu/ bionic-updates universe
# deb-src http://es.archive.ubuntu.com/ubuntu/ bionic-updates universe

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu 
## team, and may not be under a free licence. Please satisfy yourself as to 
## your rights to use the software. Also, please note that software in 
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://es.archive.ubuntu.com/ubuntu/ bionic multiverse
# deb-src http://es.archive.ubuntu.com/ubuntu/ bionic multiverse
deb http://es.archive.ubuntu.com/ubuntu/ bionic-updates multiverse
# deb-src http://es.archive.ubuntu.com/ubuntu/ bionic-updates multiverse

## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://es.archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe multiverse
# deb-src http://es.archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe multiverse

## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu bionic partner
# deb-src http://archive.canonical.com/ubuntu bionic partner

deb http://security.ubuntu.com/ubuntu bionic-security main restricted
# deb-src http://security.ubuntu.com/ubuntu bionic-security main restricted
deb http://security.ubuntu.com/ubuntu bionic-security universe
# deb-src http://security.ubuntu.com/ubuntu bionic-security universe
deb http://security.ubuntu.com/ubuntu bionic-security multiverse
# deb-src http://security.ubuntu.com/ubuntu bionic-security multiverse

If the folder sources.list exist, delete it. Make sure you are deleting the folder and not the file with the same name!

Now go to the folder sources.list.d and check that you have a file called syncthing.list. If you do, then all good. Otherwise you'd need to execute again

echo "deb https://apt.syncthing.net/ syncthing stable" | sudo tee /etc/apt/sources.list.d/syncthing.list

Everything is back to normal now. If you don't get new updates it's because there aren't any