E Unable to locate package expect code example
Example 1: E Unable to locate package sl
sudo apt update
Example 2: e unable to locate package pyrit in ubuntu
sudo su
cd /etc/apt/
ls
nano source.list
You should be able to use any of the listed mirrors by adding a line to your /etc/apt/sources.list
like this : deb http://cz.archive.ubuntu.com/ubuntu bionic main universe
Replacing cz.archive.ubuntu.com/ubuntu with the mirror in question.
./source.list
sudo apt update
sudo apt-get install pyrit