So you ran do-release-upgrade but it didn’t work?
sudo apt-get update sudo apt-get upgrade sudo apt-get install update-manager-core sudo do-release-upgrade
Some useful logs are located under /var/log/dist-upgrade/ and I bet you are going to find there something along these lines:
Error authenticating some packages It was not possible to authenticate some packages. This may be a transient network problem. You may want to try again later. See below for a list of unauthenticated packages
Temporary workaround, create file
filled with the following
Now your sudo do-release-upgrade should run OK
Make sure to remove this file once upgrade process is completed.
And if this helped don’t forget to leave a comment 😉