Last week I tried to install Ulauncher into a Linux Mint 21 freshly installed. After installing Ulauncher using: sudo add-apt-repository ppa:agornostal/ulauncher && sudo apt update && sudo apt install ulauncher I got this error: «Warning apt-key is deprecated«. After some Googling, I found this that help me to fix it. Fixing process: $ sudo apt-key list Now, we need to remember the last 8 Hexa digits (99503176) of the corresponding