Hello all, as I promised, I always like to write about every issue I faced and could solve in the past. Most of the issues I faced couldn’t bring to this place because of the business and laziness to log in to this blog. Maybe most of these are not needed and popular, but I know how much time may it take to solve this kind of an issue.
Let’s get into the topic right now. the issue caused for this is just a file. I faced this issue after upgrading ubuntu 18.04 from ubuntu 16. I didn’t think it will go well. But It did.
there is a file of ubuntu-esm-infra-trusty in the /etc/apt/preferences.d/ folder that contains a pin with no value on its priority. So if you can delete it using the following method, then after you run the same command (apt update or upgrade or any), you won’t see the same issue again and again.