- AppCenter is empty, only the installed software is shown.
- I can't add repositories. I get the message 'sudo: add-apt-repository: command not found'.
sudo apt install software-properties-commondoesn't work either. I get the message 'E: Unable to locate package software-properties-common'
AppCenter displayed the installed apps only. Running
sudo apt update did not solve the problem. I had to reinstall AppCenter to fix it.
sudo apt purge appcenter
sudo apt install appcenter
sudo apt update